diff options
Diffstat (limited to 'bin/ksh/sh.1tbl')
| -rw-r--r-- | bin/ksh/sh.1tbl | 3906 |
1 files changed, 0 insertions, 3906 deletions
diff --git a/bin/ksh/sh.1tbl b/bin/ksh/sh.1tbl deleted file mode 100644 index 0dd3e8d4fab..00000000000 --- a/bin/ksh/sh.1tbl +++ /dev/null @@ -1,3906 +0,0 @@ -.\" $OpenBSD: sh.1tbl,v 1.62 2005/02/05 12:36:21 jmc Exp $ -.\" -.\" Public Domain -.\" -.Dd August 19, 1996 -.Dt SH 1 -.Os -.Sh NAME -.Nm sh -.Nd public domain Bourne shell -.Sh SYNOPSIS -.Nm sh -.Op Fl +abCefhiklmnprsuvxX -.Op Fl +o Ar option -.Xo -.Bk -words -.Oo Oo Fl c Ar command-string -.Op Ar command-name -.Li \&| Fl s -.Li \&| Ar file Oc -.Ek -.Op Ar argument ... Oc -.Xc -.Sh DESCRIPTION -.Nm -is a reimplementation of the Bourne shell, a command interpreter for both -interactive and script use. -.Ss Shell startup -The following options can be specified only on the command line: -.Bl -tag -width Ds -.It Fl c Ar command-string -.Nm -will execute the command(s) contained in -.Ar command-string . -.It Fl i -Interactive mode; see below. -.It Fl l -Login shell; see below. -.It Fl s -The shell reads commands from standard input; all non-option arguments -are positional parameters. -.It Fl r -Restricted mode; see below. -.El -.Pp -In addition to the above, the options described in the -.Ic set -built-in command can also be used on the command line. -.Pp -If neither the -.Fl c -nor the -.Fl s -option is specified, the first non-option argument specifies the name -of a file the shell reads commands from. -If there are no non-option -arguments, the shell reads commands from the standard input. -The name of -the shell (i.e., the contents of -.Ic $0 ) -is determined as follows: if the -.Fl c -option is used and there is a non-option argument, it is used as the name; -if commands are being read from a file, the file is used as the name; -otherwise, the name the shell was called with (i.e., -.Li argv[0] ) -is used. -.Pp -A shell is -.Dq interactive -if the -.Fl i -option is used or if both standard input and standard error are attached -to a -.Xr tty 4 . -An interactive shell has job control enabled (if available), ignores the -.Dv SIGINT , -.Dv SIGQUIT , -and -.Dv SIGTERM -signals, and prints prompts before reading input (see -.Ev PS1 -and -.Ev PS2 -parameters). -For non-interactive shells, the -.Ic trackall -option is on by default (see the -.Ic set -command below). -.Pp -A shell is -.Dq restricted -if the -.Fl r -option is used or if either the basename of the name the shell was invoked -with or the -.Ev SHELL -parameter match the pattern -.Dq \&*r\&*sh -(e.g., -.Dq rsh , -.Dq rksh , -.Dq rpdksh , -etc.). -The following restrictions come into effect after the shell processes any -profile and -.Ev ENV -files: -.Pp -.Bl -bullet -compact -.It -The -.Ic cd -command is disabled. -.It -The -.Ev SHELL , -.Ev ENV , -and -.Ev PATH -parameters cannot be changed. -.It -Command names can't be specified with absolute or relative paths. -.It -The -.Fl p -option of the built-in command -.Ic command -can't be used. -.It -Redirections that create files can't be used (i.e., -.Ql > , -.Ql >| , -.Ql >> , -.Ql <> ) . -.El -.Pp -A shell is -.Dq privileged -if the -.Fl p -option is used or if the real user ID or group ID does not match the -effective user ID or group ID (see -.Xr getuid 2 -and -.Xr getgid 2 ) . -A privileged shell does not process -.Pa $HOME/.profile -nor the -.Ev ENV -parameter (see below). -Instead, the file -.Pa /etc/suid_profile -is processed. -Clearing the privileged option causes the shell to set -its effective user ID (group ID) to its real user ID (group ID). -.Pp -If the basename of the name the shell is called with (i.e., -.Li argv[0] ) -starts with -.Ql - -or if the -.Fl l -option is used, -the shell is assumed to be a login shell and the shell reads and executes -the contents of -.Pa /etc/profile -and -.Pa $HOME/.profile -if they exist and are readable. -.Pp -If the -.Ev ENV -parameter is set when the shell starts (or, in the case of login shells, -after any profiles are processed), its value is subjected to parameter, -command, arithmetic, and tilde -.Pq Sq \&~ -substitution and the resulting file -(if any) is read and executed. -If the -.Ev ENV -parameter is not set (and not -.Dv NULL ) -and -.Nm pdksh -was compiled with the -.Dv DEFAULT_ENV -macro defined, the file named in that macro is included (after the above -mentioned substitutions have been performed). -.Pp -The exit status of the shell is 127 if the command file specified on the -command line could not be opened, or non-zero if a fatal syntax error -occurred during the execution of a script. -In the absence of fatal errors, -the exit status is that of the last command executed, or zero, if no -command is executed. -.Ss Command syntax -The shell begins parsing its input by breaking it into -.Em words . -Words, which are sequences of characters, are delimited by unquoted whitespace -characters (space, tab, and newline) or meta-characters -.Po -.Ql < , -.Ql > , -.Ql | , -.Ql \&; , -.Ql ( , -and -.Ql \&) -.Pc . -Aside from delimiting words, spaces and tabs are ignored, while newlines -usually delimit commands. -The meta-characters are used in building the following tokens: -.Ql < , -.Ql <& , -.Ql << , -.Ql > , -.Ql >& , -.Ql >> , -etc. are used to specify redirections (see -.Sx Input/output redirection -below); -.Ql | -is used to create pipelines; -.Ql \&; -is used to separate commands; -.Ql & -is used to create asynchronous pipelines; -.Ql && -and -.Ql || -are used to specify conditional execution; -.Ql \&;\&; -is used in -.Ic case -statements; -and lastly, -.Ql \&( .. \&) -is used to create subshells. -.Pp -Whitespace and meta-characters can be quoted individually using a backslash -.Pq Sq \e , -or in groups using double -.Pq Sq \&" -or single -.Pq Sq \&' -quotes. -Note that the following characters are also treated specially by the -shell and must be quoted if they are to represent themselves: -.Ql \e , -.Ql \&" , -.Ql ' , -.Ql # , -.Ql $ , -.Ql ` , -.Ql ~ , -.Ql { , -.Ql } , -.Ql * , -.Ql \&? , -and -.Ql [ . -The first three of these are the above mentioned quoting characters (see -.Sx Quoting -below); -.Ql # , -if used at the beginning of a word, introduces a comment \(em everything after -the -.Ql # -up to the nearest newline is ignored; -.Ql $ -is used to introduce parameter, command, and arithmetic substitutions (see -.Sx Substitution -below); -.Ql ` -introduces an old-style command substitution (see -.Sx Substitution -below); -.Ql ~ -begins a directory expansion (see -.Sx Tilde expansion -below); -.Ql { -and -.Ql } -delimit -.Xr csh 1 -style alterations (see -.Sx Brace expansion -below); -and finally, -.Ql * , -.Ql \&? , -and -.Ql [ -are used in file name generation (see -.Sx File name patterns -below). -.Pp -As words and tokens are parsed, the shell builds commands, of which there -are two basic types: -.Em simple-commands , -typically programs that are executed, and -.Em compound-commands , -such as -.Ic for -and -.Ic if -statements, grouping constructs, and function definitions. -.Pp -A simple-command consists of some combination of parameter assignments -(see -.Sx Parameters -below), -input/output redirections (see -.Sx Input/output redirections -below), -and command words; the only restriction is that parameter assignments come -before any command words. -The command words, if any, define the command -that is to be executed and its arguments. -The command may be a shell built-in -command, a function or an external command (i.e., a separate executable file -that is located using the -.Ev PATH -parameter (see -.Sx Command execution -below)). -Note that all command constructs have an exit status: for external commands, -this is related to the status returned by -.Xr wait 2 -(if the command could not be found, the exit status is 127; if it could not -be executed, the exit status is 126); the exit status of other command -constructs (built-in commands, functions, compound-commands, pipelines, lists, -etc.) are all well-defined and are described where the construct is -described. -The exit status of a command consisting only of parameter -assignments is that of the last command substitution performed during the -parameter assignment or 0 if there were no command substitutions. -.Pp -Commands can be chained together using the -.Ql | -token to form pipelines, in which the standard output of each command but the -last is piped (see -.Xr pipe 2 ) -to the standard input of the following command. -The exit status of a pipeline is that of its last command. -A pipeline may be prefixed by the -.Ql \&! -reserved word, which causes the exit status of the pipeline to be logically -complemented: if the original status was 0, the complemented status will be 1; -if the original status was not 0, the complemented status will be 0. -.Pp -.Em Lists -of commands can be created by separating pipelines by any of the following -tokens: -.Ql && , -.Ql || , -.Ql & , -.Ql |& , -and -.Ql \&; . -The first two are for conditional execution: -.Dq Ar cmd1 No && Ar cmd2 -executes -.Ar cmd2 -only if the exit status of -.Ar cmd1 -is zero; -.Ql || -is the opposite \(em -.Ar cmd2 -is executed only if the exit status of -.Ar cmd1 -is non-zero. -.Ql && -and -.Ql || -have equal precedence which is higher than that of -.Ql & , -.Ql |& , -and -.Ql \&; , -which also have equal precedence. -Note that the -.Ql && -and -.Ql || -operators are -.Qq left-associative . -For example, both of these commands will print only -.Qq bar : -.Bd -literal -offset indent -false && echo foo || echo bar -true || echo foo && echo bar -.Ed -.Pp -The -.Ql & -token causes the preceding command to be executed asynchronously; that is, -the shell starts the command but does not wait for it to complete (the shell -does keep track of the status of asynchronous commands, see -.Sx Job control -below). -When an asynchronous command is started when job control is disabled -(i.e., in most scripts), the command is started with signals -.Dv SIGINT -and -.Dv SIGQUIT -ignored and with input redirected from -.Pa /dev/null -(however, redirections specified in the asynchronous command have precedence). -Note that a command must follow the -.Ql && -and -.Ql || -operators, while it need not follow -.Ql & , -.Ql |& , -or -.Ql \&; . -The exit status of a list is that of the last command executed, with the -exception of asynchronous lists, for which the exit status is 0. -.Pp -Compound commands are created using the following reserved words. -These words -are only recognized if they are unquoted and if they are used as the first -word of a command (i.e., they can't be preceded by parameter assignments or -redirections): -.Bd -unfilled -offset center -.Bf Sy -case else function ! -do esac if time [[ -done fi in until { -elif for then while } -.Ef -.Ed -.Sy Note: -Some shells (but not this one) execute control structure commands in a -subshell when one or more of their file descriptors are redirected, so any -environment changes inside them may fail. -To be portable, the -.Ic exec -statement should be used instead to redirect file descriptors before the -control structure. -.Pp -In the following compound command descriptions, command lists (denoted as -.Em list ) -that are followed by reserved words must end with a semicolon, a newline, or -a (syntactically correct) reserved word. -For example, -.Bd -unfilled -offset indent -.Ic { echo foo; echo bar; } -.Ic { echo foo; echo bar<newline> } -.Ic { { echo foo; echo bar; } } -.Ed -.Pp -are all valid, but -.Bd -unfilled -offset indent -.Ic { echo foo; echo bar } -.Ed -.Pp -is not. -.Bl -tag -width Ds -.It Ic \&( Ar list Ic \&) -Execute -.Ar list -in a subshell. -There is no implicit way to pass environment changes from a -subshell back to its parent. -.It Ic \&{ Ar list Ic \&} -Compound construct; -.Ar list -is executed, but not in a subshell. -Note that -.Ic \&{ -and -.Ic \&} -are reserved words, not meta-characters. -.It Xo Ic case Ar word Ic in [ -.Ns [ Ic \&( ] Ar pattern [ -.Ns Ic \&| Ar pattern ] ... Ic \&) -.Ar list Ic \&;\&; -.Ns ] Ar ... -.Ic esac -.Xc -The -.Ic case -statement attempts to match -.Ar word -against the specified -.Ar pattern Ns s ; -the -.Ar list -associated with the first successfully matched pattern is executed. -Patterns used in -.Ic case -statements are the same as those used for file name patterns except that the -restrictions regarding -.Ql \&. -and -.Ql / -are dropped. -Note that any unquoted space before and after a pattern is -stripped; any space within a pattern must be quoted. -Both the word and the -patterns are subject to parameter, command, and arithmetic substitution, as -well as tilde substitution. -For historical reasons, open and close braces may be used instead of -.Ic in -and -.Ic esac -(e.g., -.Ic case $foo { *) echo bar; } ) . -The exit status of a -.Ic case -statement is that of the executed -.Ar list ; -if no -.Ar list -is executed, the exit status is zero. -.It Xo Ic for Ar name No [ -.Ic in Ar word ... term Ns ] -.Ic do Ar list Ic done -.Xc -For each -.Ar word -in the specified word list, the parameter -.Ar name -is set to the word and -.Ar list -is executed. -If -.Ic in -is not used to specify a word list, the positional parameters -.Po -.Ic $1 , $2 , -etc.\& -.Pc -are used instead. -For historical reasons, open and close braces may be used instead of -.Ic do -and -.Ic done -(e.g., -.Ic for i\&; { echo $i; } ) . -The exit status of a -.Ic for -statement is the last exit status of -.Ar list ; -if -.Ar list -is never executed, the exit status is zero. -.Ar term -is either a newline or a -.Ql \&; . -.It Xo Ic if Ar list Ic then -.Ar list [ Ic elif Ar list Ic then -.Ar list ] Ar ... [ Ic else -.Ar list ] Ic fi -.Xc -If the exit status of the first -.Ar list -is zero, the second -.Ar list -is executed; otherwise, the -.Ar list -following the -.Ic elif , -if any, is executed with similar consequences. -If all the lists following the -.Ic if -and -.Ic elif Ns s -fail (i.e., exit with non-zero status), the -.Ar list -following the -.Ic else -is executed. -The exit status of an -.Ic if -statement is that of non-conditional -.Ar list -that is executed; if no non-conditional -.Ar list -is executed, the exit status is zero. -.It Xo Ic until Ar list Ic do Ar list -.Ic done -.Xc -This works like -.Ic while , -except that the body is executed only while the exit status of the first -.Ar list -is non-zero. -.It Xo Ic while Ar list Ic do Ar list -.Ic done -.Xc -A -.Ic while -is a pre-checked loop. -Its body is executed as often as the exit status of the first -.Ar list -is zero. -The exit status of a -.Ic while -statement is the last exit status of the -.Ar list -in the body of the loop; if the body is not executed, the exit status is zero. -.It Xo Ic function Ar name Ic \&{ -.Ar list Ic \&} -.Xc -Defines the function -.Ar name -(see -.Sx Functions -below). -Note that redirections specified after a function definition are -performed whenever the function is executed, not when the function definition -is executed. -.It Ar name Ic () Ar command -Mostly the same as -.Ic function -(see -.Sx Functions -below). -.El -.Ss Quoting -Quoting is used to prevent the shell from treating characters or words -specially. -There are three methods of quoting. -First, -.Ql \e -quotes the following character, unless it is at the end of a line, in which -case both the -.Ql \e -and the newline are stripped. -Second, a single quote -.Pq Sq ' -quotes everything up to the next single quote (this may span lines). -Third, a double quote -.Pq Sq \&" -quotes all characters, except -.Ql $ , -.Ql ` -and -.Ql \e , -up to the next unquoted double quote. -.Ql $ -and -.Ql ` -inside double quotes have their usual meaning (i.e., parameter, command or -arithmetic substitution) except no field splitting is carried out on the -results of double-quoted substitutions. -If a -.Ql \e -inside a double-quoted string is followed by -.Ql \e , -.Ql $ , -.Ql ` , -or -.Ql \&" , -it is replaced by the second character; if it is followed by a newline, both -the -.Ql \e -and the newline are stripped; otherwise, both the -.Ql \e -and the character following are unchanged. -.Pp -.Sy Note: -See -.Sx POSIX mode -below for a special rule regarding sequences of the form -.Ic \&"...`...\e\&"...`..\&" . -.Ss Aliases -There are two types of aliases: normal command aliases and tracked aliases. -Command aliases are normally used as a short hand for a long or often used -command. -The shell expands command aliases (i.e., substitutes the alias name -for its value) when it reads the first word of a command. -An expanded alias is re-processed to check for more aliases. -If a command alias ends in a -space or tab, the following word is also checked for alias expansion. -The alias expansion process stops when a word that is not an alias is found, -when a quoted word is found or when an alias word that is currently being -expanded is found. -.Pp -The following command aliases are defined automatically by the shell: -.Pp -.Bl -item -offset indent -compact -.It -.Ic hash='alias -t' -.It -.Ic type='whence -v' -.El -.Pp -Tracked aliases allow the shell to remember where it found a particular -command. -The first time the shell does a path search for a command that is -marked as a tracked alias, it saves the full path of the command. -The next -time the command is executed, the shell checks the saved path to see that it -is still valid, and if so, avoids repeating the path search. -Tracked aliases can be listed and created using -.Ic alias -t . -Note that changing the -.Ev PATH -parameter clears the saved paths for all tracked aliases. -If the -.Ic trackall -option is set (i.e., -.Ic set Fl o Ic trackall -or -.Ic set Fl h ) , -the shell tracks all commands. -This option is set automatically for non-interactive shells. -For interactive shells, only the following commands are -automatically tracked: -.Ic cat , cc , chmod , cp , -.Ic date , ed , emacs , grep , -.Ic ls , mail , make , mv , -.Ic pr , rm , sed , sh , -.Ic vi , -and -.Ic who . -.Ss Substitution -The first step the shell takes in executing a simple-command is to perform -substitutions on the words of the command. -There are three kinds of -substitution: parameter, command, and arithmetic. -Parameter substitutions, -which are described in detail in the next section, take the form -.Ic $ Ns Ar name -or -.Ic ${ Ns Ar ... Ns Ic \&} ; -command substitutions take the form -.Ic $( Ns Ar command Ns Ic \&) -or -.Ic ` Ns Ar command Ns Ic ` ; -and arithmetic substitutions take the form -.Ic $(( Ns Ar expression Ns Ic )) . -.Pp -If a substitution appears outside of double quotes, the results of the -substitution are generally subject to word or field splitting according to -the current value of the -.Ev IFS -parameter. -The -.Ev IFS -parameter specifies a list of characters which are used to break a string up -into several words; any characters from the set space, tab, and newline that -appear in the -.Ev IFS -characters are called -.Dq IFS whitespace . -Sequences of one or more -.Ev IFS -whitespace characters, in combination with zero or one -.Pf non- Ev IFS -whitespace -characters, delimit a field. -As a special case, leading and trailing -.Ev IFS -whitespace is stripped (i.e., no leading or trailing empty field is created by -it); leading -.Pf non- Ev IFS -whitespace does create an empty field. -.Pp -Example: If -.Ev IFS -is set to -.Dq <space>: , -and VAR is set to -.Dq <space>A<space>:<space><space>B::D , -the substitution for $VAR results in four fields: -.Sq A , -.Sq B , -.Sq -(an empty field), -and -.Sq D . -Note that if the -.Ev IFS -parameter is set to the -.Dv NULL -string, no field splitting is done; if the parameter is unset, the default -value of space, tab, and newline is used. -.Pp -Also, note that the field splitting applies only to the immediate result of -the substitution. -Using the previous example, the substitution for $VAR:E -results in the fields: -.Sq A , -.Sq B , -.Sq , -and -.Sq D:E , -not -.Sq A , -.Sq B , -.Sq , -and -.Sq E . -This behavior is POSIX compliant, but incompatible with some other shell -implementations which do field splitting on the word which contained the -substitution or use -.Dv IFS -as a general whitespace delimiter. -.Pp -The results of substitution are, unless otherwise specified, also subject to -brace expansion and file name expansion (see the relevant sections below). -.Pp -A command substitution is replaced by the output generated by the specified -command, which is run in a subshell. -For -.Ic $( Ns Ar command Ns Ic \&) -substitutions, normal quoting rules are used when -.Ar command -is parsed; however, for the -.Ic ` Ns Ar command Ns Ic ` -form, a -.Ql \e -followed by any of -.Ql $ , -.Ql ` , -or -.Ql \e -is stripped (a -.Ql \e -followed by any other character is unchanged). -As a special case in command substitutions, a command of the form -.Ic \&< Ar file -is interpreted to mean substitute the contents of -.Ar file -(note that -.Ic $(< foo) -has the same effect as -.Ic $(cat foo) , -but it is carried out more efficiently because no process is started). -.Pp -.Sy Note: -.Ic $( Ns Ar command Ns Ic \&) -expressions are currently parsed by finding the matching parenthesis, -regardless of quoting. -This should be fixed soon. -.Pp -Arithmetic substitutions are replaced by the value of the specified expression. -For example, the command -.Ic echo $((2+3*4)) -prints 14. -See -.Sx Arithmetic expressions -for a description of an expression. -.Ss Parameters -Parameters are shell variables; they can be assigned values and their values -can be accessed using a parameter substitution. -A parameter name is either one -of the special single punctuation or digit character parameters described -below, or a letter followed by zero or more letters or digits -.Po -.Ql _ -counts as a letter -.Pc . -Parameter substitutions take the form -.Ic $ Ns Ar name -or -.Ic ${ Ns Ar name Ns Ic \&} , -where -.Ar name -is a parameter name. -If substitution is performed on a parameter -that is not set, a null string is substituted unless the -.Ic nounset -option -.Po -.Ic set Fl o Ic nounset -or -.Ic set Fl u -.Pc -is set, in which case an error occurs. -.Pp -Parameters can be assigned values in a number of ways. -First, the shell implicitly sets some parameters like -.Ic # , PWD , -etc.; this is the only way the special single character parameters are set. -Second, parameters are imported from the shell's environment at startup. -Third, parameters can be assigned values on the command line, for example, -.Ic FOO=bar -sets the parameter -.Ev FOO -to -.Dq bar ; -multiple parameter assignments can be given on a single command line and they -can be followed by a simple-command, in which case the assignments are in -effect only for the duration of the command (such assignments are also -exported, see below for implications of this). -Note that both the parameter name and the -.Ql = -must be unquoted for the shell to recognize a parameter assignment. -The fourth way of setting a parameter is with the -.Ic export , -.Ic readonly -and -.Ic typeset -commands; see their descriptions in the -.Sx Command execution -section. -Fifth, -.Ic for -loops set parameters as well as the -.Ic getopts , -.Ic read -and -.Ic set Fl A -commands. -Lastly, parameters can be assigned values using assignment operators -inside arithmetic expressions (see -.Sx Arithmetic expressions -below) or using the -.Xo Ic ${ Ns Ar name Ns = -.Ns Ar value Ns Ic \&} -.Xc -form of the parameter substitution (see below). -.Pp -Parameters with the export attribute (set using the -.Ic export -or -.Ic typeset Fl x -commands, or by parameter assignments followed by simple commands) are put in -the environment (see -.Xr environ 7 ) -of commands run by the shell as -.Ar name Ns = Ns Ar value -pairs. -The order in which parameters appear in the environment of a command is -unspecified. -When the shell starts up, it extracts parameters and their values -from its environment and automatically sets the export attribute for those -parameters. -.Pp -Modifiers can be applied to the -.Ic ${ Ns Ar name Ns Ic \&} -form of parameter substitution: -.Bl -tag -width Ds -.It Xo Ic ${ Ns Ar name Ns -.Ic \&:\&- Ns Ar word Ns Ic \&} -.Xc -If -.Ar name -is set and not -.Dv NULL , -it is substituted; otherwise, -.Ar word -is substituted. -.It Xo Ic ${ Ns Ar name Ns -.Ic \&:\&+ Ns Ar word Ns Ic \&} -.Xc -If -.Ar name -is set and not -.Dv NULL , -.Ar word -is substituted; otherwise, nothing is substituted. -.It Xo Ic ${ Ns Ar name Ns -.Ic \&:\&= Ns Ar word Ns Ic \&} -.Xc -If -.Ar name -is set and not -.Dv NULL , -it is substituted; otherwise, it is assigned -.Ar word -and the resulting value of -.Ar name -is substituted. -.It Xo Ic ${ Ns Ar name Ns -.Ic \&:\&? Ns Ar word Ns Ic \&} -.Xc -If -.Ar name -is set and not -.Dv NULL , -it is substituted; otherwise, -.Ar word -is printed on standard error (preceded by -.Ar name Ns \&: ) -and an error occurs (normally causing termination of a shell script, function -or .-script). -If word is omitted the string -.Dq parameter null or not set -is used instead. -.El -.Pp -In the above modifiers, the -.Ql \&: -can be omitted, in which case the conditions only depend on -.Ar name -being set (as opposed to set and not -.Dv NULL ) . -If -.Ar word -is needed, parameter, command, arithmetic, and tilde substitution are performed -on it; if -.Ar word -is not needed, it is not evaluated. -.Pp -The following forms of parameter substitution can also be used: -.Bl -tag -width Ds -.It Ic ${# Ns Ar name Ns Ic \&} -The number of positional parameters if -.Ar name -is -.Ql * , -.Ql @ , -not specified, or the length of the string value of parameter -.Ar name . -.It Xo Ic ${# Ns Ar name Ns -.Ic [*\&]} , ${# Ns Ar name Ns Ic [@\&]} -.Xc -The number of elements in the array -.Ar name . -.Sm off -.It Xo -.Ic ${ Ar name Ic # Ar pattern -.Sm on -.Ic } , -.Sm off -.Ic ${ Ar name Ic ## Ar pattern Ic \&} -.Xc -.Sm on -If -.Ar pattern -matches the beginning of the value of parameter -.Ar name , -the matched text is deleted from the result of substitution. -A single -.Ql # -results in the shortest match, and two -of them result in the longest match. -.Sm off -.It Xo -.Ic ${ Ar name Ic % Ar pattern -.Sm on -.Ic } , -.Sm off -.Ic ${ Ar name Ic %% Ar pattern Ic } -.Xc -.Sm on -Like -.Ic ${..#..} -substitution, but it deletes from the end of the value. -.El -.Pp -The following special parameters are implicitly set by the shell and cannot be -set directly using assignments: -.Bl -tag -width "1 ... 9" -.It Ev \&! -Process ID of the last background process started. -If no background processes have been started, the parameter is not set. -.It Ev \&# -The number of positional parameters (i.e., -.Ic $1 , $2 , -etc.). -.It Ev \&$ -The process ID of the shell, or the -.Tn PID -of the original shell if it is a subshell. -Do -.Em NOT -use this mechanism for generating temporary file names; see -.Xr mktemp 1 -instead. -.It Ev \&- -The concatenation of the current single letter options (see the -.Ic set -command below for a list of options). -.It Ev \&? -The exit status of the last non-asynchronous command executed. -If the last command was killed by a signal, -.Ic \&$?\& -is set to 128 plus the signal number. -.It Ev 0 -The name the shell was invoked with (i.e., -.Li argv[0] ) , -or the -.Ar command-name -if it was invoked with the -.Fl c -option and the -.Ar command-name -was supplied, or the -.Ar file -argument, if it was supplied. -If the -.Ic posix -option is not set, -.Ic \&$0 -is the name of the current function or script. -.It Ev 1 ... Ev 9 -The first nine positional parameters that were supplied to the shell, function -or .-script. -Further positional parameters may be accessed using -.Ic ${ Ns Ar number Ns Ic \&} . -.It Ev \&* -All positional parameters (except parameter 0); i.e., -.Ic $1 , $2 , $3 , -\&... -If used -outside of double quotes, parameters are separate words (which are subjected -to word splitting); if used within double quotes, parameters are separated -by the first character of the -.Ev IFS -parameter (or the empty string if -.Ev IFS -is -.Dv NULL ) . -.It Ev \&@ -Same as -.Ic \&$\&* , -unless it is used inside double quotes, in which case a separate word is -generated for each positional parameter. -If there are no positional parameters, no word is generated. -.Ic \&$\&@ -can be used to access arguments, verbatim, without losing -.Dv NULL -arguments or splitting arguments with spaces. -.El -.Pp -The following parameters are set and/or used by the shell: -.Bl -tag -width "EXECSHELL" -.It Ev CDPATH -Search path for the -.Ic cd -built-in command. -Works the same way as -.Ev PATH -for those directories not beginning with -.Ql / -in -.Ic cd -commands. -Note that if -.Ev CDPATH -is set and does not contain -.Dq \&. -or contains an empty path, the current directory is not searched. -Also, the -.Ic cd -built-in command will display the resulting directory when a match is found -in any search path other than the empty path. -.It Ev COLUMNS -Set to the number of columns on the terminal or window. -Currently set to the -.Dq cols -value as reported by -.Xr stty 1 -if that value is non-zero. -This parameter is used by the -.Ic set Fl o -and -.Ic kill Fl l -commands to format information columns. -.It Ev ENV -If this parameter is found to be set after any profile files are executed, the -expanded value is used as a shell startup file. -It typically contains function and alias definitions. -.It Ev ERRNO -Integer value of the shell's -.Va errno -variable. -It indicates the reason the last system call failed. -Not yet implemented. -.It Ev EXECSHELL -If set, this parameter is assumed to contain the shell that is to be used to -execute commands that -.Xr execve 2 -fails to execute and which do not start with a -.Dq \&#\&! Ns Ar shell -sequence. -.It Ev FCEDIT -The editor used by the -.Ic fc -command (see below). -.It Ev FPATH -Like -.Ev PATH , -but used when an undefined function is executed to locate the file defining the -function. -It is also searched when a command can't be found using -.Ev PATH . -See -.Sx Functions -below for more information. -.It Ev HOME -The default directory for the -.Ic cd -command and the value substituted for an unqualified -.Ic ~ -(see -.Sx Tilde expansion -below). -.It Ev IFS -Internal field separator, used during substitution and by the -.Ic read -command, to split values into distinct arguments; normally set to space, tab -and newline. -See -.Sx Substitution -above for details. -.Pp -.Sy Note: -This parameter is not imported from the environment when the shell is -started. -.It Ev SH_VERSION -The version of shell and the date the version was created (read-only). -.It Ev LINENO -The line number of the function or shell script that is currently being -executed. -.It Ev LINES -Set to the number of lines on the terminal or window. -Not yet implemented. -.It Ev OLDPWD -The previous working directory. -Unset if -.Ic cd -has not successfully changed directories since the shell started, or if the -shell doesn't know where it is. -.It Ev OPTARG -When using -.Ic getopts , -it contains the argument for a parsed option, if it requires one. -.It Ev OPTIND -The index of the last argument processed when using -.Ic getopts . -Assigning 1 to this parameter causes -.Ic getopts -to process arguments from the beginning the next time it is invoked. -.It Ev PATH -A colon separated list of directories that are searched when looking for -commands and .'d files. -An empty string resulting from a leading or trailing -colon, or two adjacent colons, is treated as a -.Dq \&. , -the current directory. -.It Ev POSIXLY_CORRECT -If set, this parameter causes the -.Ic posix -option to be enabled. -See -.Sx POSIX mode -below. -.It Ev PPID -The process ID of the shell's parent (read-only). -.It Ev PS1 -The primary prompt for interactive shells. -Parameter, command, and arithmetic -substitutions are performed. -.Ql \&! -is replaced with the current command number (see the -.Ic fc -command below). -A literal -.Ql \&! -can be put in the prompt by placing -.Ql !! -in -.Ev PS1 . -The default is -.Dq \&$\ \& -for non-root users, -.Dq \&#\ \& -for root. -.It Ev PS2 -Secondary prompt string, by default -.Dq \&>\ \& , -used when more input is needed to complete a command. -.It Ev PS4 -Used to prefix commands that are printed during execution tracing (see the -.Ic set Fl x -command below). -The prompt is printed verbatim (i.e., no substitutions are done). -Default is -.Dq \&+\ \& . -.It Ev PWD -The current working directory. -May be unset or -.Dv NULL -if the shell doesn't know where it is. -.It Ev REPLY -Default parameter for the -.Ic read -command if no names are given. -.It Ev TMPDIR -The directory shell temporary files are created in. -If this parameter is not -set, or does not contain the absolute path of a writable directory, temporary -files are created in -.Pa /tmp . -.El -.Ss Tilde expansion -Tilde expansion, which is done in parallel with parameter substitution, is done -on words starting with an unquoted -.Ql ~ . -The characters following the tilde, up to the first -.Ql / , -if any, are assumed to be a login name. -If the login name is empty, -.Ql + -or -.Ql - , -the value of the -.Ev HOME , -.Ev PWD , -or -.Ev OLDPWD -parameter is substituted, respectively. -Otherwise, the password file is -searched for the login name, and the tilde expression is substituted with the -user's home directory. -If the login name is not found in the password file or -if any quoting or parameter substitution occurs in the login name, no -substitution is performed. -.Pp -In parameter assignments (those preceding a simple-command or those occurring -in the arguments of -.Ic alias , -.Ic export , -.Ic readonly , -and -.Ic typeset ) , -tilde expansion is done after any unquoted colon -.Pq Sq \&: , -and login names are also delimited by colons. -.Pp -The home directory of previously expanded login names are cached and re-used. -The -.Ic alias -d -command may be used to list, change, and add to this cache (e.g., -.Ic alias -d fac=/usr/local/facilities; cd ~fac/bin ) . -.Ss File name patterns -A file name pattern is a word containing one or more unquoted -.Ql \&? -or -.Ql * -characters or -.Dq [..] -sequences. -Once brace expansion has been performed, the shell replaces file -name patterns with the sorted names of all the files that match the pattern -(if no files match, the word is left unchanged). -The pattern elements have the following meaning: -.Bl -tag -width Ds -.It Ic \&? -Matches any single character. -.It Ic \&* -Matches any sequence of characters. -.It Ic \&[ Ns .. Ns Ic \&] -Matches any of the characters inside the brackets. -Ranges of characters can be -specified by separating two characters by a -.Ql - -(e.g., -.Dq [a0-9] -matches the letter -.Dq a -or any digit). -In order to represent itself, a -.Ql - -must either be quoted or the first or last character in the character list. -Similarly, a -.Ql \&] -must be quoted or the first character in the list if it is to represent itself -instead of the end of the list. -Also, a -.Ql \&! -appearing at the start of the list has special meaning (see below), so to -represent itself it must be quoted or appear later in the list. -.It Ic \&[\&! Ns .. Ns Ic \&] -Like -.Ic \&[ Ns .. Ns Ic \&] , -except it matches any character not inside the brackets. -.Sm off -.It Xo Ic \&*( Ar pattern Ic \&| No \ ...\ -.Ic \&| Ar pattern Ic \&) -.Xc -.Sm on -Matches any string of characters that matches zero or more occurrences of the -specified patterns. -Example: The pattern -.Ic \&*(foo\&|bar) -matches the strings -.Dq , -.Dq foo , -.Dq bar , -.Dq foobarfoo , -etc. -.Sm off -.It Xo Ic \&+( Ar pattern Ic \&| No \ ...\ -.Ic \&| Ar pattern Ic \&) -.Xc -.Sm on -Matches any string of characters that matches one or more occurrences of the -specified patterns. -Example: The pattern -.Ic \&+(foo\&|bar) -matches the strings -.Dq foo , -.Dq bar , -.Dq foobar , -etc. -.Sm off -.It Xo Ic \&?( Ar pattern Ic \&| No \ ...\ -.Ic \&| Ar pattern Ic \&) -.Xc -.Sm on -Matches the empty string or a string that matches one of the specified -patterns. -Example: The pattern -.Ic \&?(foo\&|bar) -only matches the strings -.Dq , -.Dq foo -and -.Dq bar . -.Sm off -.It Xo Ic \&@( Ar pattern Ic \&| No \ ...\ -.Ic \&| Ar pattern Ic \&) -.Xc -.Sm on -Matches a string that matches one of the specified patterns. -Example: The pattern -.Ic \&@(foo\&|bar) -only matches the strings -.Dq foo -and -.Dq bar . -.Sm off -.It Xo Ic \&!( Ar pattern Ic \&| No \ ...\ -.Ic \&| Ar pattern Ic \&) -.Xc -.Sm on -Matches any string that does not match one of the specified patterns. -Examples: The pattern -.Ic \&!(foo\&|bar) -matches all strings except -.Dq foo -and -.Dq bar ; -the pattern -.Ic \&!(\&*) -matches no strings; the pattern -.Ic \&!(\&?)\&* -matches all strings (think about it). -.El -.Pp -Note that -.Nm pdksh -currently never matches -.Dq \&. -and -.Dq \&.\&. , -but the original -.Xr ksh , -Bourne -.Xr sh , -and -.Xr bash -do, so this may have to change (too bad). -.Pp -Note that none of the above pattern elements match either a period -.Pq Sq \&. -at the start of a file name or a slash -.Pq Sq / , -even if they are explicitly used in a -.Ic \&[ Ns .. Ns Ic \&] -sequence; also, the names -.Dq \&. -and -.Dq \&.\&. -are never matched, even by the pattern -.Dq \&.\&* . -.Pp -If the -.Ic markdirs -option is set, any directories that result from file name generation are marked -with a trailing -.Ql / . -.Pp -The -.Tn POSIX -character classes (i.e., -.Ic \&[\&: Ns Ar class-name Ns Ic \&:\&] -inside a -.Ic \&[ Ns .. Ns Ic \&] -expression) are not yet implemented. -.Ss Input/output redirection -When a command is executed, its standard input, standard output, and standard -error (file descriptors 0, 1, and 2, respectively) are normally inherited from -the shell. -Three exceptions to this are commands in pipelines, for which -standard input and/or standard output are those set up by the pipeline, -asynchronous commands created when job control is disabled, for which standard -input is initially set to be from -.Pa /dev/null , -and commands for which any of the following redirections have been specified: -.Bl -tag -width Ds -.It Ic \&> Ar file -Standard output is redirected to -.Ar file . -If -.Ar file -does not exist, it is created; if it does exist, is a regular file and the -.Ic noclobber -option is set, an error occurs; otherwise, the file is truncated. -Note that this means the command -.Ic cmd < foo > foo -will open -.Ar foo -for reading and then truncate it when it opens it for writing, before -.Ar cmd -gets a chance to actually read -.Ar foo . -.It Ic \&>\&| Ar file -Same as -.Ic \&> , -except the file is truncated, even if the -.Ic noclobber -option is set. -.It Ic \&>\&> Ar file -Same as -.Ic \&> , -except if -.Ar file -exists it is appended to instead of being truncated. -Also, the file is opened -in append mode, so writes always go to the end of the file (see -.Xr open 2 ) . -.It Ic \&< Ar file -Standard input is redirected from -.Ar file , -which is opened for reading. -.It Ic \&<\&> Ar file -Same as -.Ic \&< , -except the file is opened for reading and writing. -.It Ic \&<\&< Ar marker -After reading the command line containing this kind of redirection (called a -.Dq here document ) , -the shell copies lines from the command source into a temporary file until a -line matching -.Ar marker -is read. -When the command is executed, standard input is redirected from the -temporary file. -If -.Ar marker -contains no quoted characters, the contents of the temporary file are processed -as if enclosed in double quotes each time the command is executed, so -parameter, command, and arithmetic substitutions are performed, along with -backslash -.Pq Sq \e -escapes for -.Ql $ , -.Ql ` , -.Ql \e , -and -.Ql \enewline . -If multiple here documents are used on the same command line, they are saved in -order. -.It Ic \&<\&<\&- Ar marker -Same as -.Ic \&<\&< , -except leading tabs are stripped from lines in the here document. -.It Ic \&<\&& Ar fd -Standard input is duplicated from file descriptor -.Ar fd . -.Ar fd -can be a single digit, indicating the number of an existing file descriptor; -the letter -.Ql p , -indicating the file descriptor associated with the output of the current -co-process; or the character -.Ql - , -indicating standard input is to be closed. -.It Ic \&>\&& Ar fd -Same as -.Ic \&<\&& , -except the operation is done on standard output. -.El -.Pp -In any of the above redirections, the file descriptor that is redirected (i.e., -standard input or standard output) can be explicitly given by preceding the -redirection with a single digit. -Parameter, command, and arithmetic -substitutions, tilde substitutions, and (if the shell is interactive) -file name generation are all performed on the -.Ar file , -.Ar marker , -and -.Ar fd -arguments of redirections. -Note, however, that the results of any file name -generation are only used if a single file is matched; if multiple files match, -the word with the expanded file name generation characters is used. -Note -that in restricted shells, redirections which can create files cannot be used. -.Pp -For simple-commands, redirections may appear anywhere in the command; for -compound-commands -.Po -.Ic if -statements, etc. -.Pc , -any redirections must appear at the end. -Redirections are processed after -pipelines are created and in the order they are given, so -.Pp -.Dl Ic cat /foo/bar 2\*(Gt&1 \*(Gt /dev/null \&| cat -n -.Pp -will print an error with a line number prepended to it. -.Ss Arithmetic expressions -Integer arithmetic expressions can be used with the -.Ic let -command, inside -.Ic $(( Ns .. Ns Ic )) -expressions, inside array references (e.g., -.Sm off -.Ar name Ic \&[ Ar expr Ic \&] ) , -.Sm on -as numeric arguments to the -.Ic test -command, and as the value of an assignment to an integer parameter. -.Pp -Expressions may contain alpha-numeric parameter identifiers, array references, -and integer constants and may be combined with the following C operators -(listed and grouped in increasing order of precedence): -.Pp -Unary operators: -.Bl -item -offset indent -compact -.It -.Ic \&+ \&- \&! \&~ \&+\&+ \&-\&- -.El -.Pp -Binary operators: -.Bl -item -offset indent -compact -.It -.Ic \&, -.It -.Ic = \&*= /= %= \&+= \&-= \&<\&<= -.Ic \&>\&>= \&&= ^= \&|= -.It -.Ic \&|\&| -.It -.Ic \&&\&& -.It -.Ic \&| -.It -.Ic ^ -.It -.Ic \&& -.It -.Ic == \&!= -.It -.Ic \&< \&<= \&>= \&> -.It -.Ic \&<\&< \&>\&> -.It -.Ic \&+ \&- -.It -.Ic \&* / % -.El -.Pp -Ternary operators: -.Bl -item -offset indent -compact -.It -.Ic \&?\&: -(precedence is immediately higher than assignment) -.El -.Pp -Grouping operators: -.Bl -item -offset indent -compact -.It -.Ic \&( \&) -.El -.Pp -Integer constants may be specified with arbitrary bases using the notation -.Ar base Ns Ic \&# Ns Ar number , -where -.Ar base -is a decimal integer specifying the base, and -.Ar number -is a number in the specified base. -Additionally, -integers may be prefixed with -.Sq 0X -or -.Sq 0x -(specifying base 16) -or -.Sq 0 -(base 8) -in all forms of arithmetic expressions, -except as numeric arguments to the -.Ic test -command. -.Pp -The operators are evaluated as follows: -.Bl -tag -width Ds -offset indent -.It unary Ic \&+ -Result is the argument (included for completeness). -.It unary Ic \&- -Negation. -.It Ic \&! -Logical -.Tn NOT ; -the result is 1 if argument is zero, 0 if not. -.It Ic \&~ -Arithmetic (bit-wise) -.Tn NOT . -.It Ic \&+\&+ -Increment; must be applied to a parameter (not a literal or other expression). -The parameter is incremented by 1. -When used as a prefix operator, the result -is the incremented value of the parameter; when used as a postfix operator, the -result is the original value of the parameter. -.It Ic \&-\&- -Similar to -.Ic \&+\&+ , -except the parameter is decremented by 1. -.It Ic \&, -Separates two arithmetic expressions; the left-hand side is evaluated first, -then the right. -The result is the value of the expression on the right-hand side. -.It Ic = -Assignment; variable on the left is set to the value on the right. -.It Xo Ic \&*= /= \&+= \&-= \&<\&<= -.Ic \&>\&>= \&&= ^= \&|= -.Xc -Assignment operators. -.Ao Ar var Ac -.Ao Ar op Ac = -.Ao Ar expr Ac -is the same as -.Ao Ar var Ac = -.Ao Ar var Ac -.Ao Ar op Ac -.Ic \&( -.Ao Ar expr Ac -.Ic \&) . -.It Ic \&|\&| -Logical -.Tn OR ; -the result is 1 if either argument is non-zero, 0 if not. -The right argument is evaluated only if the left argument is zero. -.It Ic \&&\&& -Logical -.Tn AND ; -the result is 1 if both arguments are non-zero, 0 if not. -The right argument is evaluated only if the left argument is non-zero. -.It Ic \&| -Arithmetic (bit-wise) -.Tn OR . -.It Ic ^ -Arithmetic (bit-wise) -.Tn XOR -(exclusive-OR). -.It Ic \&& -Arithmetic (bit-wise) -.Tn AND . -.It Ic == -Equal; the result is 1 if both arguments are equal, 0 if not. -.It Ic \&!= -Not equal; the result is 0 if both arguments are equal, 1 if not. -.It Ic \&< -Less than; the result is 1 if the left argument is less than the right, 0 if -not. -.It Ic \&<= \&>= \&> -Less than or equal, greater than or equal, greater than. -See -.Ic \&< . -.It Ic \&<\&< \&>\&> -Shift left (right); the result is the left argument with its bits shifted left -(right) by the amount given in the right argument. -.It Ic \&+ \&- \&* / -Addition, subtraction, multiplication, and division. -.It Ic % -Remainder; the result is the remainder of the division of the left argument by -the right. -The sign of the result is unspecified if either argument is negative. -.It Xo Ao Ar arg1 Ac Ic \ \&? -.Ao Ar arg2 Ac Ic \ \&: Ao Ar arg3 Ac -.Xc -If -.Ao Ar arg1 Ac -is non-zero, the result is -.Ao Ar arg2 Ac , -otherwise -.Ao Ar arg3 Ac . -.El -.Ss Functions -Functions are defined using either Korn shell -.Ic function Ar name -syntax or the Bourne/POSIX shell -.Fn name -syntax (see below for the difference between the two forms). -Functions are like -.Li .-scripts -in that they are executed in the current environment. -However, unlike -.Li .-scripts , -shell arguments (i.e., positional parameters -.Ic $1 , $2 , -etc.) are never visible -inside them. -When the shell is determining the location of a command, functions -are searched after special built-in commands, before regular and -non-regular built-ins, and before the -.Ev PATH -is searched. -.Pp -An existing function may be deleted using -.Ic unset Fl f Ar function-name . -A list of functions can be obtained using -.Ic typeset \&+f -and the function definitions can be listed using -.Ic typeset \&-f . -The -.Ic autoload -command (which is an alias for -.Ic typeset \&-fu ) -may be used to create undefined functions; when an undefined function is -executed, the shell searches the path specified in the -.Ev FPATH -parameter for a file with the same name as the function, which, if found, is -read and executed. -If after executing the file the named function is found to -be defined, the function is executed; otherwise, the normal command search is -continued (i.e., the shell searches the regular built-in command table and -.Ev PATH ) . -Note that if a command is not found using -.Ev PATH , -an attempt is made to autoload a function using -.Ev FPATH -(this is an undocumented feature of the original Korn shell). -.Pp -Functions can have two attributes, -.Dq trace -and -.Dq export , -which can be set with -.Ic typeset \&-ft -and -.Ic typeset \&-fx , -respectively. -When a traced function is executed, the shell's -.Ic xtrace -option is turned on for the function's duration; otherwise, the -.Ic xtrace -option is turned off. -The -.Dq export -attribute of functions is currently not used. -In the original Korn shell, -exported functions are visible to shell scripts that are executed. -.Pp -Since functions are executed in the current shell environment, parameter -assignments made inside functions are visible after the function completes. -If this is not the desired effect, the -.Ic typeset -command can be used inside a function to create a local parameter. -Note that special parameters (e.g., -.Ic \&$$ , $\&! ) -can't be scoped in this way. -.Pp -The exit status of a function is that of the last command executed in the -function. -A function can be made to finish immediately using the -.Ic return -command; this may also be used to explicitly specify the exit status. -.Pp -Functions defined with the -.Ic function -reserved word are treated differently in the following ways from functions -defined with the -.Ic \&(\&) -notation: -.Bl -bullet -.It -The -.Ic $0 -parameter is set to the name of the function (Bourne-style functions -leave -.Ic $0 -untouched). -.It -Parameter assignments preceding function calls are not kept in the shell -environment (executing Bourne-style functions will keep assignments). -.It -.Ev OPTIND -is saved/reset and restored on entry and exit from the function so -.Ic getopts -can be used properly both inside and outside the function (Bourne-style -functions leave -.Dv OPTIND -untouched, so using -.Ic getopts -inside a function interferes with using -.Ic getopts -outside the function). -In the future, the following differences will also be added: -.Bl -bullet -offset indent -.It -A separate trap/signal environment will be used during the execution of -functions. -This will mean that traps set inside a function will not affect the -shell's traps and signals that are not ignored in the shell (but may be -trapped) will have their default effect in a function. -.It -The EXIT trap, if set in a function, will be executed after the function -returns. -.El -.El -.Ss POSIX mode -The shell is intended to be -.Tn POSIX -compliant; however, in some cases, -.Tn POSIX -behaviour is contrary either to the original Korn shell behaviour or to user -convenience. -How the shell behaves in these cases is determined by the state of the -.Ic posix -option -.Pq Ic set Fl o Ic posix . -If it is on, the -.Tn POSIX -behaviour is followed; otherwise, it is not. -The -.Ic posix -option is set automatically when the shell starts up if the environment -contains the -.Dv POSIXLY_CORRECT -parameter. (The shell can also be compiled so that it is in -.Tn POSIX -mode by default; however, this is usually not desirable). -.Pp -The following is a list of things that are affected by the state of the -.Ic posix -option: -.Bl -bullet -.It -Reading of -.Ev $ENV . -If not in -.Ic posix -mode, the -.Ev ENV -parameter is not expanded and included when the shell starts. -.It -Occurrences of -.Ic \e\&" -inside double quoted -.Ic `\&.\&.` -command substitutions. -In -.Tn POSIX -mode, the -.Ic \e\&" -is interpreted when the command is interpreted; in -.Pf non- Tn POSIX -mode, the -backslash is stripped before the command substitution is interpreted. -For example, -.Ic echo \&"`echo \e\&"hi\e\&"`\&" -produces -.Dq \&"hi\&" -in -.Tn POSIX -mode, -.Dq hi -in -.Pf non- Tn POSIX -mode. -To avoid problems, use the -.Ic $(...)\& -form of command substitution. -.It -.Ic kill -l -output. -In -.Tn POSIX -mode, signal names are listed one per line; in -.Pf non- Tn POSIX -mode, -signal numbers, names, and descriptions are printed in columns. -In the future, a new option -.Po Fl v -\ perhaps -.Pc -will be added to distinguish the two behaviours. -.It -.Ic fg -exit status. -In -.Tn POSIX -mode, the exit status is 0 if no errors occur; in -.Pf non- Tn POSIX -mode, the exit status is that of the last foregrounded job. -.It -.Ic getopts . -In -.Tn POSIX -mode, options must start with a -.Ql - ; -in -.Pf non- Tn POSIX -mode, options can start with either -.Ql - -or -.Ql + . -.It -Brace expansion (also known as alternation). -In -.Tn POSIX -mode, brace expansion is -disabled; in -.Pf non- Tn POSIX -mode, brace expansion is enabled. -Note that -.Ic set Fl o Ic posix -(or setting the -.Ev POSIXLY_CORRECT -parameter) automatically turns the -.Ic braceexpand -option off; however, it can be explicitly turned on later. -.It -.Ic set \&- . -In -.Tn POSIX -mode, this does not clear the -.Ic verbose -or -.Ic xtrace -options; in -.Pf non- Tn POSIX -mode, it does. -.It -.Ic set -exit status. -In -.Tn POSIX -mode, the exit status of -.Ic set -is 0 if there are no errors; in -.Pf non- Tn POSIX -mode, the exit status is that of any -command substitutions performed in generating the -.Ic set -command. -For example, -.Ic set \&-\&- `false`; echo $?\& -prints 0 in -.Tn POSIX -mode, 1 in -.Pf non- Tn POSIX -mode. -This construct is used in most shell scripts that use the old -.Xr getopt 1 -command. -.It -Argument expansion of the -.Ic alias , -.Ic export , -.Ic readonly , -and -.Ic typeset -commands. -In -.Tn POSIX -mode, normal argument expansion is done; in -.Pf non- Tn POSIX -mode, -field splitting, file globbing, brace expansion, and (normal) tilde expansion -are turned off, while assignment tilde expansion is turned on. -.It -Signal specification. -In -.Tn POSIX -mode, signals can be specified as digits, only -if signal numbers match -.Tn POSIX -values (i.e., HUP=1, INT=2, QUIT=3, ABRT=6, -KILL=9, ALRM=14, and TERM=15); in -.Pf non- Tn POSIX -mode, signals can always be digits. -.It -Alias expansion. -In -.Tn POSIX -mode, alias expansion is only carried out when -reading command words; in -.Pf non- Tn POSIX -mode, alias expansion is carried out on any -word following an alias that ended in a space. -For example, the following -.Ic for -loop -.Pp -.Bl -item -offset indent -compact -.It -.Ic alias a='for ' i='j' -.It -.Xo -.Ic a i in 1 2; do echo i=$i j=$j; -.Ic done -.Xc -.El -.Pp -uses parameter -.Ic i -in -.Tn POSIX -mode, -.Ic j -in -.Pf non- Tn POSIX -mode. -.It -Test. -In -.Tn POSIX -mode, the expression -.Sq Fl t -(preceded by some number of -.Sq Ic \&! -arguments) is always true as it is a non-zero length string; in -.Pf non- Tn POSIX -mode, it tests if file descriptor 1 is a -.Xr tty 4 -(i.e., the -.Ar fd -argument to the -.Fl t -test may be left out and defaults to 1). -.El -.Ss Command execution -After evaluation of command-line arguments, redirections, and parameter -assignments, the type of command is determined: a special built-in, a -function, a regular built-in, or the name of a file to execute found using the -.Ev PATH -parameter. -The checks are made in the above order. -Special built-in commands differ from other commands in that the -.Ev PATH -parameter is not used to find them, and an error during their execution can -cause a non-interactive shell to exit and parameter assignments that are -specified before the command are kept after the command completes. -Just to confuse things, if the -.Ic posix -option is turned off (see the -.Ic set -command below), some special commands are very special in that no field -splitting, file globbing, brace expansion, nor tilde expansion is performed -on arguments that look like assignments. -Regular built-in commands are different only in that the -.Ev PATH -parameter is not used to find them. -.Pp -The original -.Nm ksh -and -.Tn POSIX -differ somewhat in which commands are considered -special or regular: -.Pp -.Tn POSIX -special commands -.Pp -.Ic \&. , \&: , break , continue , -.Ic eval , exec , exit , export , -.Ic readonly , return , set , shift , -.Ic trap , unset -.Pp -Additional -.Nm -special commands -.Pp -.Ic builtin , times , typeset -.Pp -Very special commands -.Pq Pf non- Tn POSIX -.Pp -.Ic alias , readonly , set , typeset -.Pp -.Tn POSIX -regular commands -.Pp -.Ic alias , bg , cd , command , -.Ic false , fc , fg , getopts , -.Ic jobs , kill , read , true , -.Ic umask , unalias , wait -.Pp -Additional -.Nm -regular commands -.Pp -.Ic \&[ , echo , let , print , -.Ic pwd , test , ulimit , whence -.Pp -In the future, the additional -.Nm -special and regular commands may be treated -differently from the -.Tn POSIX -special and regular commands. -.Pp -Once the type of the command has been determined, any command-line parameter -assignments are performed and exported for the duration of the command. -.Pp -The following describes the special and regular built-in commands: -.Bl -tag -width Ds -.It Ic \&. Ar file Op Ar arg1 ... -Execute the commands in -.Ar file -in the current environment. -The file is searched for in the directories of -.Ev PATH . -If arguments are given, the positional parameters may be used to access them -while -.Ar file -is being executed. -If no arguments are given, the positional parameters are -those of the environment the command is used in. -.It Ic \&: Op Ar ... -The null command. -Exit status is set to zero. -.It Xo Ic alias -.Op Fl d | Ic +-t Op Fl r -.Op Ic +-px -.Op Ic +- -.Oo Ar name -.Op Ns = Ns Ar value -.Ar ... Oc -.Xc -Without arguments, -.Ic alias -lists all aliases. -For any name without a value, the existing alias is listed. -Any name with a value defines an alias (see -.Sx Aliases -above). -.Pp -When listing aliases, one of two formats is used. -Normally, aliases are listed as -.Ar name Ns = Ns Ar value , -where -.Ar value -is quoted. -If options were preceded with -.Ql + , -or a lone -.Ql + -is given on the command line, only -.Ar name -is printed. -In addition, if the -.Fl p -option is used, each alias is prefixed with the string -.Dq alias\ \& . -.Pp -The -.Fl x -option sets -.Po Ic \&+x -\ clears -.Pc -the export attribute of an alias, or, if no names are given, lists the aliases -with the export attribute (exporting an alias has no effect). -.Pp -The -.Fl t -option indicates that tracked aliases are to be listed/set (values specified on -the command line are ignored for tracked aliases). -The -.Fl r -option indicates that all tracked aliases are to be reset. -.Pp -The -.Fl d -option causes directory aliases, which are used in tilde expansion, to be -listed or set (see -.Sx Tilde expansion -above). -.It Ic bg Op Ar job ... -Resume the specified stopped job(s) in the background. -If no jobs are specified, -.Ic %\&+ -is assumed. -This command is only available on systems which support job control (see -.Sx Job control -below for more information). -.It Ic break Op Ar level -Exit the -.Ar level Ns th -inner-most -.Ic for , -.Ic until , -or -.Ic while -loop. -.Ar level -defaults to 1. -.It Ic builtin Ar command Op Ar arg1 ... -Execute the built-in command -.Ar command . -.It Xo Ic cd Op Fl LP -.Op Ar dir -.Xc -Set the working directory to -.Ar dir . -If the parameter -.Ev CDPATH -is set, it lists the search path for the directory containing -.Ar dir . -A -.Dv NULL -path means the current directory. -If -.Ar dir -is found in any component of the -.Ev CDPATH -search path other than the -.Dv NULL -path, the name of the new working directory will be written to standard output. -If -.Ar dir -is missing, the home directory -.Ev HOME -is used. -If -.Ar dir -is -.Ql - , -the previous working directory is used (see -.Ev OLDPWD -parameter). -If the -.Fl L -option (logical path) is used or if the -.Ic physical -option (see the -.Ic set -command below) isn't set, references to -.Dq \&.\&. -in -.Ar dir -are relative to the path used to get to the directory. -If the -.Fl P -option (physical path) is used or if the -.Ic physical -option is set, -.Dq \&.\&. -is relative to the filesystem directory tree. -The -.Ev PWD -and -.Ev OLDPWD -parameters are updated to reflect the current and old working directory, -respectively. -.It Xo Ic cd Op Fl LP -.Ar old new -.Xc -The string -.Ar new -is substituted for -.Ar old -in the current directory, and the shell attempts to change to the new -directory. -.It Xo Ic command Op Fl p -.Ar cmd Op Ar arg1 ... -.Xc -.Ar cmd -is executed exactly as if -.Ic command -had not been specified, with two exceptions. -First, -.Ar cmd -cannot be a shell function, and second, special built-in commands lose their -specialness (i.e., redirection and utility errors do not cause the shell to -exit, and command assignments are not permanent). -If the -.Fl p -option is given, a default search path is used instead of the current value of -.Ev PATH -(the actual value of the default path is system dependent: on -.Tn POSIX Ns ish -systems, it is the value returned by -.Ic getconf CS_PATH ) . -.It Ic continue Op Ar level -Jumps to the beginning of the -.Ar level Ns th -inner-most -.Ic for , -.Ic until , -or -.Ic while -loop. -.Ar level -defaults to 1. -.It Xo Ic echo Op Fl neE -.Op Ar arg ... -.Xc -Prints its arguments (separated by spaces) followed by a newline, to the -standard output. -The newline is suppressed if any of the arguments contain the -backslash sequence -.Ql \ec . -See the -.Ic print -command below for a list of other backslash sequences that are recognized. -.Pp -The options are provided for compatibility with -.Bx -shell scripts. -The -.Fl n -option suppresses the trailing newline, -.Fl e -enables backslash interpretation (a no-op, since this is normally done), and -.Fl E -suppresses backslash interpretation. -.It Ic eval Ar command ... -The arguments are concatenated (with spaces between them) to form a single -string which the shell then parses and executes in the current environment. -.It Xo Ic exec -.Op Ar command Op Ar arg ... -.Xc -The command is executed without forking, replacing the shell process. -.Pp -If no command is given except for I/O redirection, the I/O redirection is -permanent and the shell is -not replaced. -Any file descriptors which are opened or -.Xr dup 2 Ns 'd -in this way are made available to other executed commands (note that the Korn -shell differs here: it does not pass on file descriptors greater than 2). -.It Ic exit Op Ar status -The shell exits with the specified exit status. -If -.Ar status -is not specified, the exit status is the current value of the -.Ic $?\& -parameter. -.It Xo Ic export Op Fl p -.Op Ar parameter Ns Op \&= Ns Ar value -.Xc -Sets the export attribute of the named parameters. -Exported parameters are passed in the environment to executed commands. -If values are specified, the named parameters are also assigned. -.Pp -If no parameters are specified, the names of all parameters with the export -attribute are printed one per line, unless the -.Fl p -option is used, in which case -.Ic export -commands defining all exported parameters, including their values, are printed. -.It Ic false -A command that exits with a non-zero status. -.It Xo Ic fc -.Oo Fl e No \&- \&| Fl s Oc -.Op Fl g -.Op Ar old Ns = Ns Ar new -.Op Ar prefix -.Xc -Re-execute the selected command (the previous command by default) after -performing the optional substitution of -.Ar old -with -.Ar new . -If -.Fl g -is specified, all occurrences of -.Ar old -are replaced with -.Ar new . -This command is usually accessed with the predefined -.Ic alias r='fc -e -' . -.It Ic fg Op Ar job ... -Resume the specified job(s) in the foreground. -If no jobs are specified, -.Ic %\&+ -is assumed. -This command is only available on systems which support job control (see -.Sx Job control -below for more information). -.It Xo Ic getopts Ar optstring name -.Op Ar arg ... -.Xc -Used by shell procedures to parse the specified arguments (or positional -parameters, if no arguments are given) and to check for legal options. -.Ar optstring -contains the option letters that -.Ic getopts -is to recognize. -If a letter is followed by a colon, the option is expected to -have an argument. -Options that do not take arguments may be grouped in a single argument. -If an option takes an argument and the option character is not the -last character of the argument it is found in, the remainder of the argument is -taken to be the option's argument; otherwise, the next argument is the option's -argument. -.Pp -Each time -.Ic getopts -is invoked, it places the next option in the shell parameter -.Ar name -and the index of the next argument to be processed in the shell parameter -.Ev OPTIND . -If the option was introduced with a -.Ql + , -the option placed in -.Ar name -is prefixed with a -.Ql + . -When an option requires an argument, -.Ic getopts -places it in the shell parameter -.Ev OPTARG . -When an illegal option or a missing option argument is encountered, a question -mark or a colon is placed in -.Ar name -(indicating an illegal option or missing argument, respectively) and -.Ev OPTARG -is set to the option character that caused the problem. -If -.Ar optstring -does not begin with a colon, a question mark is placed in -.Ar name , -.Ev OPTARG -is unset and an error message is printed to standard error. -.Pp -When the end of the options is encountered, -.Ic getopts -exits with a non-zero exit status. -Options end at the first (non-option -argument) argument that does not start with a -.Ql - , -or when a -.Ql -- -argument is encountered. -.Pp -Option parsing can be reset by setting -.Ev OPTIND -to 1 (this is done automatically whenever the shell or a shell procedure is -invoked). -.Pp -Warning: Changing the value of the shell parameter -.Ev OPTIND -to a value other than 1, or parsing different sets of arguments without -resetting -.Ev OPTIND -may lead to unexpected results. -.It Xo Ic hash Op Fl r -.Op Ar name ... -.Xc -Without arguments, any hashed executable command pathnames are listed. -The -.Fl r -option causes all hashed commands to be removed from the hash table. -Each -.Ar name -is searched as if it were a command name and added to the hash table if it is -an executable command. -.It Xo Ic jobs Op Fl lpn -.Op Ar job ... -.Xc -Display information about the specified job(s); if no jobs are specified, all -jobs are displayed. -The -.Fl n -option causes information to be displayed only for jobs that have changed -state since the last notification. -If the -.Fl l -option is used, the process ID of each process in a job is also listed. -The -.Fl p -option causes only the process group of each job to be printed. -See -.Sx Job control -below for the format of -.Ar job -and the displayed job. -.It Xo Ic kill -.Oo Fl s Ar signame \*(Ba -.Fl Ar signum | Fl Ar signame Oc { -.Ar job | -.Ar pid | -.Ar pgrp No } Ar ... -.Xc -Send the specified signal to the specified jobs, process IDs, or process -groups. -If no signal is specified, the -.Dv TERM -signal is sent. -If a job is specified, the signal is sent to the job's process group. -See -.Sx Job control -below for the format of -.Ar job . -.It Ic kill -l Op Ar exit-status ... -Print the name of the signal that killed a process which exited with the -specified -.Ar exit-status Ns es. -If no arguments are specified, a list of all the signals, their numbers and -a short description of them are printed. -.It Xo Ic print -.Oo Fl nprsu Ns Ar n \*(Ba -.Fl R Op Fl en Oc -.Op Ar argument ... -.Xc -.Ic print -prints its arguments on the standard output, separated by spaces and -terminated with a newline. -The -.Fl n -option suppresses the newline. -By default, certain C escapes are translated. -These include -.Ql \eb , -.Ql \ef , -.Ql \en , -.Ql \er , -.Ql \et , -.Ql \ev , -and -.Ql \e0### -.Po -.Ql # -is an octal digit, of which there may be 0 to 3 -.Pc . -.Ql \ec -is equivalent to using the -.Fl n -option. -.Ql \e -expansion may be inhibited with the -.Fl r -option. -The -.Fl s -option prints to the history file instead of standard output, the -.Fl u -option prints to file descriptor -.Ar n -.Po -.Ar n -defaults to 1 if omitted -.Pc , -and the -.Fl p -option prints to the co-process (see -.Sx Co-processes -above). -.Pp -The -.Fl R -option is used to emulate, to some degree, the -.Bx -.Xr echo 1 -command, which does not process -.Ql \e -sequences unless the -.Fl e -option is given. -As above, the -.Fl n -option suppresses the trailing newline. -.It Ic pwd Op Fl LP -Print the present working directory. -If the -.Fl L -option is used or if the -.Ic physical -option (see the -.Ic set -command below) isn't set, the logical path is printed (i.e., the path used to -.Ic cd -to the current directory). -If the -.Fl P -option (physical path) is used or if the -.Ic physical -option is set, the path determined from the filesystem (by following -.Dq \&.\&. -directories to the root directory) is printed. -.It Xo Ic read Oo Fl prsu Ns Ar n -.Oc Op Ar parameter ... -.Xc -Reads a line of input from the standard input, separates the line into fields -using the -.Ev IFS -parameter (see -.Sx Substitution -above), and assigns each field to the specified parameters. -If there are more parameters than fields, the extra parameters are set to -.Dv NULL , -or alternatively, if there are more fields than parameters, the last parameter -is assigned the remaining fields (inclusive of any separating spaces). -If no parameters are specified, the -.Ev REPLY -parameter is used. -If the input line ends in a backslash and the -.Fl r -option was not used, the backslash and the newline are stripped and more input -is read. -If no input is read, -.Ic read -exits with a non-zero status. -.Pp -The first parameter may have a question mark and a string appended to it, in -which case the string is used as a prompt (printed to standard error before -any input is read) if the input is a -.Xr tty 4 -(e.g., -.Ic read nfoo?'number of foos: ' ) . -.Pp -The -.Fl u Ns Ar n -and -.Fl p -options cause input to be read from file descriptor -.Ar n -or the current co-process (see -.Sx Co-processes -above for comments on this), respectively. -If the -.Fl s -option is used, input is saved to the history file. -.It Xo Ic readonly Op Fl p -.Oo Ar parameter -.Op Ns = Ns Ar value -.Ar ... Oc -.Xc -Sets the read-only attribute of the named parameters. -If values are given, -parameters are set to them before setting the attribute. -Once a parameter is -made read-only, it cannot be unset and its value cannot be changed. -.Pp -If no parameters are specified, the names of all parameters with the read-only -attribute are printed one per line, unless the -.Fl p -option is used, in which case -.Ic readonly -commands defining all read-only parameters, including their values, are -printed. -.It Ic return Op Ar status -Returns from a function or -.Ic .\& -script, with exit status -.Ar status . -If no -.Ar status -is given, the exit status of the last executed command is used. -If used outside of a function or -.Ic .\& -script, it has the same effect as -.Ic exit . -Note that -.Nm pdksh -treats both profile and -.Ev ENV -files as -.Ic .\& -scripts, while the original Korn shell only treats profiles as -.Ic .\& -scripts. -.It Xo Ic set Op Ic +-abCefhkmnpsuvxX -.Op Ic +-o Ar option -.Op Ic +-A Ar name -.Op Fl \&- -.Op Ar arg ... -.Xc -The -.Ic set -command can be used to set -.Pq Ic \&- -or clear -.Pq Ic \&+ -shell options, set the positional parameters, or set an array parameter. -Options can be changed using the -.Ic \&+ Ns Fl o Ar option -syntax, where -.Ar option -is the long name of an option, or using the -.Ic \&+\&- Ns Ar letter -syntax, where -.Ar letter -is the option's single letter name (not all options have a single letter name). -The following table lists both option letters (if they exist) and long names -along with a description of what the option does: -.Bl -tag -width 15n -.It Fl A -Sets the elements of the array parameter -.Ar name -to -.Ar arg ... . -If -.Fl A -is used, the array is reset (i.e., emptied) first; if -.Ic \&+A -is used, the first N elements are set (where N is the number of -.Ar arg Ns s ) , -the rest are left untouched. -.It Fl a Ic allexport -All new parameters are created with the export attribute. -.It Fl b Ic notify -Print job notification messages asynchronously, instead of just before the -prompt. -Only used if job control is enabled -.Pq Fl m . -.It Ic csh-history -Enables a subset of -.Xr csh 1 Ns -style -history editing using the -.Ql !\& -character. -.It Fl C Ic noclobber -Prevent -.Ic \&> -redirection from overwriting existing files -.Po -.Ic \&>\&| -must be used to force an overwrite -.Pc . -.It Fl e Ic errexit -Exit (after executing the -.Dv ERR -trap) as soon as an error occurs or a command fails (i.e., exits with a -non-zero status). -This does not apply to commands whose exit status is -explicitly tested by a shell construct such as -.Ic if , -.Ic until , -.Ic while , -.Ic \&&\&& , -or -.Ic \&|\&| -statements. -.It Fl f Ic noglob -Do not expand file name patterns. -.It Fl h Ic trackall -Create tracked aliases for all executed commands (see -.Sx Aliases -above). -Enabled by default for non-interactive shells. -.It Fl i Ic interactive -Enable interactive mode. -This can only be set/unset when the shell is invoked. -.It Fl k Ic keyword -Parameter assignments are recognized anywhere in a command. -.It Fl l Ic login -The shell is a login shell. -This can only be set/unset when the shell is invoked (see -.Sx Shell startup -above). -.It Fl m Ic monitor -Enable job control (default for interactive shells). -.It Fl n Ic noexec -Do not execute any commands. -Useful for checking the syntax of scripts -(ignored if interactive). -.It Fl p Ic privileged -Set automatically if, when the shell starts, the read UID or GID does not match -the effective UID (EUID) or GID (EGID), respectively. -See -.Sx Shell startup -above for a description of what this means. -.It Fl r Ic restricted -Enable restricted mode. -This option can only be used when the shell is invoked. -See -.Sx Shell startup -above for a description of what this means. -.It Fl s Ic stdin -If used where the shell is invoked, commands are read from standard input. -Set automatically if the shell is invoked with no arguments. -.Pp -When -.Fl s -is used with the -.Ic set -command it causes the specified arguments to be sorted before assigning them to -the positional parameters (or to array -.Ar name , -if -.Fl A -is used). -.It Fl u Ic nounset -Referencing of an unset parameter is treated as an error, unless one of the -.Ql - , -.Ql + -or -.Ql = -modifiers is used. -.It Fl v Ic verbose -Write shell input to standard error as it is read. -.It Fl x Ic xtrace -Print commands and parameter assignments when they are executed, preceded by -the value of -.Ev PS4 . -.It Fl X Ic markdirs -Mark directories with a trailing -.Ql / -during file name generation. -.It Ic bgnice -Background jobs are run with lower priority. -.It Ic ignoreeof -The shell will not exit when end-of-file is read; -.Ic exit -must be used. -.It Ic nohup -Do not kill running jobs with a -.Dv SIGHUP -signal when a login shell exists. -Currently set by default, but this will -change in the future to be compatible with the original Korn shell (which -doesn't have this option, but does send the -.Dv SIGHUP -signal). -.It Ic nolog -No effect. -In the original Korn shell, this prevents function definitions from -being stored in the history file. -.It Ic physical -Causes the -.Ic cd -and -.Ic pwd -commands to use -.Dq physical -(i.e., the filesystem's) -.Dq \&.\&. -directories instead of -.Dq logical -directories (i.e., the shell handles -.Dq \&.\&. , -which allows the user to be oblivious of symbolic links to directories). -Clear by default. -Note that setting this option does not affect the current value of the -.Ev PWD -parameter; only the -.Ic cd -command changes -.Ev PWD . -See the -.Ic cd -and -.Ic pwd -commands above for more details. -.It Ic posix -Enable -.Tn POSIX -mode. -See -.Sx POSIX mode -above. -.It Ic vi -Enable vi-like command-line editing (interactive shells only). -.It Ic viraw -No effect. -In the original Korn shell, unless -.Ic viraw -was set, the vi command-line mode would let the -.Xr tty 4 -driver do the work until -.Tn ESC -(^[) was entered. -.Nm pdksh -is always in viraw mode. -.It Ic vi-esccomplete -In vi command-line editing, do command and file name completion when escape -(^[) is entered in command mode. -.It Ic vi-show8 -Prefix characters with the eighth bit set with -.Dq M\&- . -If this option is not set, characters in the range 128\-160 are printed as is, -which may cause problems. -.It Ic vi-tabcomplete -In vi command-line editing, do command and file name completion when tab (^I) -is entered in insert mode. -.El -.Pp -These options can also be used upon invocation of the shell. -The current set of -options (with single letter names) can be found in the parameter -.Dv \&- . -.Ic set Fl o -with no option name will list all the options and whether each is on or off; -.Ic set +o -will print the long names of all options that are currently on. -.Pp -Remaining arguments, if any, are positional parameters and are assigned, in -order, to the positional parameters (i.e., -.Ic $1 , $2 , -etc.). -If options end with -.Ql -- -and there are no remaining arguments, all positional parameters are cleared. -If no options or arguments are given, the values of all names are printed. -For unknown historical reasons, a lone -.Ql - -option is treated specially \(em it clears both the -.Fl x -and -.Fl v -options. -.It Ic shift Op Ar number -The positional parameters -.Ar number Ns +1 , -.Ar number Ns +2 , -etc. are renamed to -.Dq 1 , -.Dq 2 , -etc. -.Ar number -defaults to 1. -.It Ic test Ar expression -.It Ic \&[ Ar expression Ic \&] -.Ic test -evaluates the -.Ar expression -and returns zero status if true, 1 if false, or greater than 1 if there -was an error. -It is normally used as the condition command of -.Ic if -and -.Ic while -statements. -Symbolic links are followed for all -.Ar file -expressions except -.Fl h -and -.Fl L . -.Pp -The following basic expressions are available: -.Bl -tag -width 17n -.It Fl r Ar file -.Ar file -exists and is readable. -.It Fl w Ar file -.Ar file -exists and is writable. -.It Fl x Ar file -.Ar file -exists and is executable. -.It Fl a Ar file -.Ar file -exists. -.It Fl e Ar file -.Ar file -exists. -.It Fl f Ar file -.Ar file -is a regular file. -.It Fl d Ar file -.Ar file -is a directory. -.It Fl c Ar file -.Ar file -is a character special device. -.It Fl b Ar file -.Ar file -is a block special device. -.It Fl p Ar file -.Ar file -is a named pipe. -.It Fl u Ar file -.Ar file Ns 's -mode has setuid bit set. -.It Fl g Ar file -.Ar file Ns 's -mode has setgid bit set. -.It Fl k Ar file -.Ar file Ns 's -mode has sticky bit set. -.It Fl s Ar file -.Ar file -is not empty. -.It Fl O Ar file -.Ar file Ns 's -owner is the shell's effective user ID. -.It Fl G Ar file -.Ar file Ns 's -group is the shell's effective group ID. -.It Fl h Ar file -.Ar file -is a symbolic link. -.It Fl H Ar file -.Ar file -is a context dependent directory (only useful on HP-UX). -.It Fl L Ar file -.Ar file -is a symbolic link. -.It Fl S Ar file -.Ar file -is a socket. -.It Fl o Ar option -Shell -.Ar option -is set (see the -.Ic set -command above for a list of options). -As a non-standard extension, if the option starts with a -.Ql \&! , -the test is negated; the test always fails if -.Ar option -doesn't exist (thus -.Ic \&[ -o Ar foo -.Ic -o -o \&! Ns Ar foo Ic \&] -returns true if and only if option -.Ar foo -exists). -.It Ar file1 Fl nt Ar file2 -.Ar file1 -is newer than -.Ar file2 . -.It Ar file1 Fl ot Ar file2 -.Ar file1 -is older than -.Ar file2 . -.It Ar file1 Fl ef Ar file2 -.Ar file1 -is the same file as -.Ar file2 . -.It Fl t Op Ar fd -File descriptor -.Ar fd -is a -.Xr tty 4 -device. -If the -.Ic posix -option is not set, -.Ar fd -may be left out, in which case it is taken to be 1 (the behaviour differs due -to the special -.Tn POSIX -rules described below). -.It Ar string -.Ar string -has non-zero length. -Note that there is the potential for problems if -.Ar string -turns out to be an operator (e.g., -.Fl r ) . -It is generally better to use a test like -.Sm off -.Ic \&[\ X\&" Ar string Ic \&" Ic \ \&] -.Sm on -instead (double quotes are used in case -.Ar string -contains spaces or file globbing characters). -.It Fl z Ar string -.Ar string -is empty. -.It Fl n Ar string -.Ar string -is not empty. -.It Ar string No = Ar string -Strings are equal. -.It Ar string No \&!= Ar string -Strings are not equal. -.It Ar number Fl eq Ar number -Numbers compare equal. -.It Ar number Fl ne Ar number -Numbers compare not equal. -.It Ar number Fl ge Ar number -Numbers compare greater than or equal. -.It Ar number Fl gt Ar number -Numbers compare greater than. -.It Ar number Fl le Ar number -Numbers compare less than or equal. -.It Ar number Fl \< Ar number -Numbers compare less than. -.El -.Pp -The above basic expressions, in which unary operators have precedence over -binary operators, may be combined with the following operators (listed in -increasing order of precedence): -.Pp -.Bl -tag -width "expr -o expr" -compact -.It Ar expr Fl o Ar expr -Logical -.Tn OR . -.It Ar expr Fl a Ar expr -Logical -.Tn AND . -.It Ic \&! Ar expr -Logical -.Tn NOT . -.It Ic \&( Ar expr Ic \&) -Grouping. -.El -.Pp -On operating systems not supporting -.Pa /dev/fd/ Ns Ar n -devices (where -.Ar n -is a file descriptor number), the -.Ic test -command will attempt to fake it for all tests that operate on files (except the -.Fl e -test). -For example, -.Ic \&[ -w /dev/fd/2 \&] -tests if file descriptor 2 is writable. -.Pp -Note that some special rules are applied (courtesy of -.Tn POSIX ) -if the number of -arguments to -.Ic test -or -.Ic \&[ ... \&] -is less than five; if leading -.Ql \&! -arguments can be stripped such that only one argument remains then a string -length test is performed (again, even if the argument is a unary operator); if -leading -.Ql \&! -arguments can be stripped such that three arguments remain and the second -argument is a binary operator, then the binary operation is performed (even -if the first argument is a unary operator, including an unstripped -.Ql \&! ) . -.Pp -.Sy Note: -A common mistake is to use -.Ic if \&[ $foo = bar \&] -which fails if parameter -.Ic foo -is -.Dv NULL -or unset, if it has embedded spaces (i.e., -.Ev IFS -characters), or if it is a unary operator like -.Sq Ic \&! -or -.Sq Fl n . -Use tests like -.Ic if \&[ \&"X$foo\&" = Xbar \&] -instead. -.It Ic times -Print the accumulated user and system times used both by the shell -and by processes that the shell started which have exited. -The format of the output is: -.Bd -literal -offset indent -0m0.00s 0m0.00s -0m0.00s 0m0.00s -.Ed -.It Ic trap Op Ar handler signal ... -Sets a trap handler that is to be executed when any of the specified signals are -received. -.Ar handler -is either a -.Dv NULL -string, indicating the signals are to be ignored, a minus sign -.Pq Sq \&- , -indicating that the default action is to be taken for the signals (see -.Xr signal 3 ) , -or a string containing shell commands to be evaluated and executed at the first -opportunity (i.e., when the current command completes, or before printing the -next -.Ev PS1 -prompt) after receipt of one of the signals. -.Ar signal -is the name of a signal (e.g., -.Dv PIPE -or -.Dv ALRM ) -or the number of the signal (see the -.Ic kill Fl l -command above). -There are two special signals: -.Dv EXIT -(also known as 0), which is executed when the shell is about to exit, and -.Dv ERR , -which is executed after an error occurs (an error is something that would cause -the shell to exit if the -.Fl e -or -.Ic errexit -option were see \(em see the -.Ic set -command above). -.Dv EXIT -handlers are executed in the environment of the last executed command. -Note -that for non-interactive shells, the trap handler cannot be changed for signals -that were ignored when the shell started. -.Pp -With no arguments, -.Ic trap -lists, as a series of -.Ic trap -commands, the current state of the traps that have been set since the shell -started. -Note that the output of -.Ic trap -cannot be usefully piped to another process (an artifact of the fact that -traps are cleared when subprocesses are created). -.Pp -The original Korn shell's -.Dv DEBUG -trap and the handling of -.Dv ERR -and -.Dv EXIT -traps in functions are not yet implemented. -.It Ic true -A command that exits with a zero value. -.It Xo Ic typeset -.Oo Op Ic +-Ulprtux -.Op Fl L Ns Op Ar n -.Op Fl R Ns Op Ar n -.Op Fl Z Ns Op Ar n -.Op Fl i Ns Op Ar n -.No \&| Fl f Op Fl tux Oc -.Oo Ar name -.Op Ns = Ns Ar value -.Ar ... Oc -.Xc -Display or set parameter attributes. -With no -.Ar name -arguments, parameter attributes are displayed; if no options are used, the -current attributes of all parameters are printed as -.Ic typeset -commands; if an option is given (or -.Ql - -with no option letter), all parameters and their values with the specified -attributes are printed; if options are introduced with -.Ql + , -parameter values are not printed. -.Pp -If -.Ar name -arguments are given, the attributes of the named parameters are set -.Pq Ic \&- -or cleared -.Pq Ic \&+ . -Values for parameters may optionally be specified. -If -.Ic typeset -is used inside a function, any newly created parameters are local to the -function. -.Pp -When -.Fl f -is used, -.Ic typeset -operates on the attributes of functions. -As with parameters, if no -.Ar name Ns s -are given, functions are listed with their values (i.e., definitions) unless -options are introduced with -.Ql + , -in which case only the function names are reported. -.Bl -tag -width 3n -.It Fl L Ns Ar n -Left justify attribute. -.Ar n -specifies the field width. -If -.Ar n -is not specified, the current width of a parameter (or the width of its first -assigned value) is used. -Leading whitespace (and zeros, if used with the -.Fl Z -option) is stripped. -If necessary, values are either truncated or space padded -to fit the field width. -.It Fl R Ns Ar n -Right justify attribute. -.Ar n -specifies the field width. -If -.Ar n -is not specified, the current width of a parameter (or the width of its first -assigned value) is used. -Trailing whitespace is stripped. -If necessary, values are either stripped of leading characters or space -padded to make them fit the field width. -.It Fl Z Ns Ar n -Zero fill attribute. -If not combined with -.Fl L , -this is the same as -.Fl R , -except zero padding is used instead of space padding. -.It Fl i Ns Ar n -Integer attribute. -.Ar n -specifies the base to use when displaying the integer (if not specified, the -base given in the first assignment is used). -Parameters with this attribute may -be assigned values containing arithmetic expressions. -.It Fl U -Unsigned integer attribute. -Integers are printed as unsigned values (only -useful when combined with the -.Fl i -option). -This option is not in the original Korn shell. -.It Fl f -Function mode. -Display or set functions and their attributes, instead of parameters. -.It Fl l -Lower case attribute. -All upper case characters in values are converted to lower case. -(In the original Korn shell, this parameter meant -.Dq long integer -when used with the -.Fl i -option.) -.It Fl p -Print complete -.Ic typeset -commands that can be used to re-create the attributes (but not the values) of -parameters. -This is the default action (option exists for ksh93 compatibility). -.It Fl r -Read-only attribute. -Parameters with this attribute may not be assigned to or unset. -Once this attribute is set, it cannot be turned off. -.It Fl t -Tag attribute. -Has no meaning to the shell; provided for application use. -.Pp -For functions, -.Fl t -is the trace attribute. -When functions with the trace attribute are executed, the -.Ic xtrace -.Pq Fl x -shell option is temporarily turned on. -.It Fl u -Upper case attribute. -All lower case characters in values are converted to upper case. -(In the original Korn shell, this parameter meant -.Dq unsigned integer -when used with the -.Fl i -option, which meant upper case letters would never be used for bases greater -than 10. -See the -.Fl U -option.) -.Pp -For functions, -.Fl u -is the undefined attribute. -See -.Sx Functions -above for the implications of this. -.It Fl x -Export attribute. -Parameters (or functions) are placed in the environment of -any executed commands. -Exported functions are not yet implemented. -.El -.It Xo Ic ulimit Op Fl acdfHlmnpsStv -.Op Ar value -.Xc -Display or set process limits. -If no options are used, the file size limit -.Pq Fl f -is assumed. -.Ar value , -if specified, may be either an arithmetic expression or the word -.Dq unlimited . -The limits affect the shell and any processes created by the shell after a -limit is imposed. -Note that some systems may not allow limits to be increased -once they are set. -Also note that the types of limits available are system -dependent \(em some systems have only the -.Fl f -limit. -.Bl -tag -width 5n -.It Fl a -Displays all limits; unless -.Fl H -is used, soft limits are displayed. -.It Fl H -Set the hard limit only (default is to set both hard and soft limits). -.It Fl S -Set the soft limit only (default is to set both hard and soft limits). -.It Fl c Ar n -Impose a size limit of -.Ar n -blocks on the size of core dumps. -.It Fl d Ar n -Impose a size limit of -.Ar n -kilobytes on the size of the data area. -.It Fl f Ar n -Impose a size limit of -.Ar n -blocks on files written by the shell and its child processes (files of any -size may be read). -.It Fl l Ar n -Impose a limit of -.Ar n -kilobytes on the amount of locked (wired) physical memory. -.It Fl m Ar n -Impose a limit of -.Ar n -kilobytes on the amount of physical memory used. -.It Fl n Ar n -Impose a limit of -.Ar n -file descriptors that can be open at once. -.It Fl p Ar n -Impose a limit of -.Ar n -processes that can be run by the user at any one time. -.It Fl s Ar n -Impose a size limit of -.Ar n -kilobytes on the size of the stack area. -.It Fl t Ar n -Impose a time limit of -.Ar n -.Tn CPU -seconds to be used by each process. -.It Fl v Ar n -Impose a limit of -.Ar n -kilobytes on the amount of virtual memory used. -.El -.Pp -As far as -.Ic ulimit -is concerned, a block is 512 bytes. -.It Xo Ic umask Op Fl S -.Op Ar mask -.Xc -Display or set the file permission creation mask, or umask (see -.Xr umask 2 ) . -If the -.Fl S -option is used, the mask displayed or set is symbolic; otherwise, it is an -octal number. -.Pp -Symbolic masks are like those used by -.Xr chmod 1 . -When used, they describe what permissions may be made available (as opposed to -octal masks in which a set bit means the corresponding bit is to be cleared). -For example, -.Dq ug=rwx,o= -sets the mask so files will not be readable, writable or executable by -.Dq others , -and is equivalent (on most systems) to the octal mask -.Dq 007 . -.It Xo Ic unalias Op Fl adt -.Op Ar name1 ... -.Xc -The aliases for the given names are removed. -If the -.Fl a -option is used, all aliases are removed. -If the -.Fl t -or -.Fl d -options are used, the indicated operations are carried out on tracked or -directory aliases, respectively. -.It Xo Ic unset Op Fl fv -.Ar parameter ... -.Xc -Unset the named parameters -.Po -.Fl v , -the default -.Pc -or functions -.Pq Fl f . -The exit status is non-zero if any of the parameters were already unset, zero -otherwise. -.It Ic wait Op Ar job ... -Wait for the specified job(s) to finish. -The exit status of -.Ic wait -is that of the last specified job; if the last job is killed by a signal, the -exit status is 128 + the number of the signal (see -.Ic kill -l Ar exit-status -above); if the last specified job can't be found (because it never existed, or -had already finished), the exit status of -.Ic wait -is 127. -See -.Sx Job control -below for the format of -.Ar job . -.Ic wait -will return if a signal for which a trap has been set is received, or if a -.Dv SIGHUP , -.Dv SIGINT , -or -.Dv SIGQUIT -signal is received. -.Pp -If no jobs are specified, -.Ic wait -waits for all currently running jobs (if any) to finish and exits with a zero -status. -If job monitoring is enabled, the completion status of jobs is printed -(this is not the case when jobs are explicitly specified). -.It Xo Ic whence Op Fl pv -.Op Ar name ... -.Xc -For each -.Ar name , -the type of command is listed (reserved word, built-in, alias, -function, tracked alias, or executable). -If the -.Fl p -option is used, a path search is performed even if -.Ar name -is a reserved word, alias, etc. -Without the -.Fl v -option, -.Ic whence -is similar to -.Ic command Fl v -except that -.Ic whence -will find reserved words and won't print aliases as alias commands. -With the -.Fl v -option, -.Ic whence -is the same as -.Ic command Fl V . -Note that for -.Ic whence , -the -.Fl p -option does not affect the search path used, as it does for -.Ic command . -If the type of one or more of the names could not be determined, the exit -status is non-zero. -.El -.Ss Job control -Job control refers to the shell's ability to monitor and control jobs, which -are processes or groups of processes created for commands or pipelines. -At a minimum, the shell keeps track of the status of the background (i.e., -asynchronous) jobs that currently exist; this information can be displayed -using the -.Ic jobs -commands. -If job control is fully enabled (using -.Ic set Fl m -or -.Ic set Fl o Ic monitor ) , -as it is for interactive shells, the processes of a job are placed in their -own process group. -Foreground jobs can be stopped by typing the suspend -character from the terminal (normally ^Z), jobs can be restarted in either the -foreground or background using the -.Ic fg -and -.Ic bg -commands, and the state of the terminal is saved or restored when a foreground -job is stopped or restarted, respectively. -.Pp -Note that only commands that create processes (e.g., asynchronous commands, -subshell commands, and non-built-in, non-function commands) can be stopped; -commands like -.Ic read -cannot be. -.Pp -When a job is created, it is assigned a job number. -For interactive shells, this number is printed inside -.Dq \&[..\&] , -followed by the process IDs of the processes in the job when an asynchronous -command is run. -A job may be referred to in the -.Ic bg , -.Ic fg , -.Ic jobs , -.Ic kill , -and -.Ic wait -commands either by the process ID of the last process in the command pipeline -(as stored in the -.Ic $!\& -parameter) or by prefixing the job number with a percent -sign -.Pq Sq % . -Other percent sequences can also be used to refer to jobs: -.Bl -tag -width 10n -.It Ic %\&+ -The most recently stopped job, or, if there are no stopped jobs, the oldest -running job. -.It Ic %% , % -Same as -.Ic %\&+ . -.It Ic %\&- -The job that would be the -.Ic %\&+ -job if the latter did not exist. -.It Ic % Ns Ar n -The job with job number -.Ar n . -.It Ic %\&? Ns Ar string -The job containing the string -.Ar string -(an error occurs if multiple jobs are matched). -.It Ic % Ns Ar string -The job starting with string -.Ar string -(an error occurs if multiple jobs are matched). -.El -.Pp -When a job changes state (e.g., a background job finishes or foreground job is -stopped), the shell prints the following status information: -.Bd -unfilled -offset indent -.Ic \&[ Ar number Ic \&] Ar flag status command -.Ed -.Pp -where -.Bl -tag -width "status" -.It Ar number -is the job number of the job. -.It Ar flag -is the -.Ql + -or -.Ql - -character if the job is the -.Ic %\&+ or -.Ic %\&- -job, respectively, or space if it is neither. -.It Ar status -indicates the current state of the job and can be: -.Bl -tag -width "Running" -.It Cm Running -The job has neither stopped nor exited (note that running does not necessarily -mean consuming -.Tn CPU -time \(em the process could be blocked waiting for some -event). -.It Cm Done Op Ar number -The job exited. -.Ar number -is the exit status of the job, which is omitted if the status is zero. -.It Cm Stopped Op Ar signal -The job was stopped by the indicated -.Ar signal -(if no signal is given, the job was stopped by -.Dv SIGTSTP ) . -.It Ar signal-description Op Dq core dumped -The job was killed by a signal (e.g., memory fault, hangup, etc.; use -.Ic kill -l -for a list of signal descriptions). -The -.Dq core dumped -message indicates the process created a core file. -.El -.It Ar command -is the command that created the process. -If there are multiple processes in -the job, each process will have a line showing its -.Ar command -and possibly its -.Ar status , -if it is different from the status of the previous process. -.El -.Pp -When an attempt is made to exit the shell while there are jobs in the stopped -state, the shell warns the user that there are stopped jobs and does not exit. -If another attempt is immediately made to exit the shell, the stopped jobs are -sent a -.Dv SIGHUP -signal and the shell exits. -Similarly, if the -.Ic nohup -option is not set and there are running jobs when an attempt is made to exit -a login shell, the shell warns the user and does not exit. -If another attempt -is immediately made to exit the shell, the running jobs are sent a -.Dv SIGHUP -signal and the shell exits. -.Sh FILES -.Bl -tag -width "/etc/suid_profile" -compact -.It Pa ~/.profile -.It Pa /etc/profile -.It Pa /etc/suid_profile -.El -.Sh SEE ALSO -.Xr awk 1 , -.Xr csh 1 , -.Xr ed 1 , -.Xr getconf 1 , -.Xr getopt 1 , -.Xr ksh 1 , -.Xr sed 1 , -.Xr stty 1 , -.Xr vi 1 , -.Xr dup 2 , -.Xr execve 2 , -.Xr getgid 2 , -.Xr getuid 2 , -.Xr open 2 , -.Xr pipe 2 , -.Xr wait 2 , -.Xr getopt 3 , -.Xr rand 3 , -.Xr signal 3 , -.Xr system 3 , -.Xr tty 4 , -.Xr environ 7 -.Pp -.Rs -.%A Morris Bolsky -.%A David Korn -.%T "The KornShell Command and Programming Language" -.%D 1983 -.%O "ISBN 0-13-516972-0" -.Re -.Rs -.%A Stephen G. Kochan -.%A Patrick H. Wood -.%T "UNIX Shell Programming" -.%O "Hayden" -.Re -.Rs -.%A "IEEE Inc." -.%T "IEEE Standard for Information Technology - Portable Operating System Interface (POSIX) - Part 2: Shell and Utilities" -.%D 1993 -.%O "ISBN 1-55937-266-9" -.Re -.Sh NOTES -.Nm -is implemented as a run-time option of -.Nm pdksh , -with only those -.Nm -features whose syntax or semantics are incompatible with a traditional Bourne -shell disabled. -Since this leaves some -.Nm -extensions exposed, caution should be used where backwards compatibility with -traditional Bourne or -.Tn POSIX -compliant shells is an issue. -.Sh AUTHORS -This shell is based on the public domain 7th edition Bourne shell clone by -Charles Forsyth and parts of the BRL shell by Doug A. Gwyn, Doug Kingston, -Ron Natalie, Arnold Robbins, Lou Salkind, and others. -The first release of -.Nm pdksh -was created by Eric Gisin, and it was subsequently maintained by John R.\& -MacMillan (change!john@sq.sq.com) and Simon J. Gerraty (sjg@zen.void.oz.au). -The current maintainer is Michael Rendell (michael@cs.mun.ca). -The -.Pa CONTRIBUTORS -file in the source distribution contains a more complete list of people and -their part in the shell's development. -.Sh BUGS -Any bugs in -.Nm pdksh -should be reported to pdksh@cs.mun.ca. -Please include the version of -.Nm pdksh -.Po -.Ic echo $KSH_VERSION -shows it -.Pc , -the machine, operating system, and compiler you are using and a description of -how to repeat the bug (a small shell script that demonstrates the bug is best). -The following, if relevant (if you are not sure, include them), can also be -helpful: options you are using (both -.Pa options.h -and -.Ic set Fl o Ic options ) -and a copy of your -.Pa config.h -(the file generated by the -.Pa configure -script). -New versions of -.Nm pdksh -can be obtained from ftp://ftp.cs.mun.ca/pub/pdksh. -.Pp -BTW, the most frequently reported bug is: -.Bd -literal -offset indent -$ echo hi | read a; echo $a # Does not print hi -.Ed -.Pp -I'm aware of this and there is no need to report it. |