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.\" $OpenBSD: cat.1,v 1.14 1999/08/16 18:40:00 aaron Exp $
.\" $NetBSD: cat.1,v 1.12 1995/09/27 05:38:55 cgd Exp $
.\"
.\" Copyright (c) 1989, 1990, 1993
.\" The Regents of the University of California. All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" the Institute of Electrical and Electronics Engineers, Inc.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgment:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" @(#)cat.1 8.3 (Berkeley) 5/2/95
.\"
.Dd May 2, 1995
.Dt CAT 1
.Os
.Sh NAME
.Nm cat
.Nd concatenate and print files
.Sh SYNOPSIS
.Nm cat
.Op Fl benstuv
.Op Ar
.Sh DESCRIPTION
The
.Nm
utility reads files sequentially, writing them to the standard output.
The
.Ar file
operands are processed in command-line order.
If
.Ar file
is a single dash
.Pq Sq \&-
or absent,
.Nm
reads from the standard input.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl n
Number the output lines, starting at 1.
.It Fl b
Implies the
.Fl n
option but doesn't number blank lines.
.It Fl v
Displays non-printing characters so they are visible.
Control characters print as
.Ql ^X
for control-X. The only exception is the tab character, control-I (see the
.Fl t
option). The
.Tn DEL
character (octal 0177) prints as
.Ql ^? .
.Pf Non- Ns Tn ASCII
characters (with the high bit set) are printed as
.Ql M-
(for meta) followed by the character for the low 7 bits.
.It Fl e
Implies the
.Fl v
option and also prints a dollar sign
.Pq Ql \&$
at the end of each line.
.It Fl t
Implies the
.Fl v
option and also prints tab characters as
.Ql ^I .
.It Fl s
Squeeze multiple adjacent empty lines, causing the output to be
single spaced.
.It Fl u
The
.Fl u
option guarantees that the output is unbuffered (see
.Xr setbuf 3 ) .
.El
.Pp
The
.Nm
utility exits 0 on success or >0 if an error occurred.
.Sh EXAMPLES
The command:
.Bd -literal -offset indent
.Ic cat file1
.Ed
.Pp
will print the contents of
.Ar file1
to the standard output.
.Pp
The command:
.Bd -literal -offset indent
.Ic cat file1 file2 > file3
.Ed
.Pp
will sequentially print the contents of
.Ar file1
and
.Ar file2
to the file
.Ar file3 ,
truncating
.Ar file3
if it already exists. See the manual page for your shell
.Po
i.e.,
.Xr sh 1
.Pc
for more information on redirection.
.Pp
The command:
.Bd -literal -offset indent
.Ic cat file1 - file2 - file3
.Ed
.Pp
will print the contents of
.Ar file1 ,
print data it receives from the standard input until it receives an
.Dv EOF
.Pq Sq ^D
character, print the contents of
.Ar file2 ,
read and output contents of the standard input again, then finally output
the contents of
.Ar file3 .
Note that if the standard input referred to a file, the second dash
on the command-line would have no effect, since the entire contents of the file
would have already been read and printed by
.Nm
when it encountered the first
.Ql \&-
operand.
.Sh SEE ALSO
.Xr head 1 ,
.Xr less 1 ,
.Xr more 1 ,
.Xr pr 1 ,
.Xr sh 1 ,
.Xr tail 1 ,
.Xr vis 1 ,
.Xr setbuf 3
.Rs
.%A Rob Pike
.%T "UNIX Style, or cat -v Considered Harmful"
.%J "USENIX Summer Conference Proceedings"
.%D 1983
.Re
.Sh STANDARDS
The
.Nm
utility is compliant with the
.St -p1003.2-92
specification.
.Pp
The flags
.Op Fl benstv
are extensions to the specification.
.Sh HISTORY
A
.Nm
utility appeared in Version 1 AT&T UNIX.
.Sh BUGS
Because of the shell language mechanism used to perform output
redirection, the command
.Ic cat file1 file2 > file1
will cause the original data in
.Ar file1
to be destroyed!
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