path: root/usr.bin/sudo/INSTALL

Installation instructions for Sudo 1.6.7
========================================

Sudo uses a `configure' script to probe the capabilities and type
of the system in question.  In this release, `configure' takes many
more options than it did before.  Please read this document fully
before configuring and building sudo.  You may also wish to read the
file INSTALL.configure which explains more about the `configure' script.

Simple sudo installation
========================

For most systems and configurations it is possible simply to:

    0) If you are upgrading from a previous version of sudo
       please read the info in the UPGRADE file before proceeding.

    1) If you previously ran `configure' on a different host
       you will probably want to do a `make distclean' to remove
       the old `config.cache' file.  Otherwise, `configure'
       will complain and refuse to run.  Alternately, one can
       simply `rm config.cache'.

    2) Read the `OS dependent notes' section for any particular
       "gotchas" relating to your operating system.

    3) `cd' to the source or build directory and type `./configure'
       to generate a Makefile and config.h file suitable for
       building sudo.  Before you actually run configure you
       should read the `Available configure options' section
       to see if there are any special options you may want
       or need.

    4) Edit the configure-generated Makefile if you wish to
       change any of the default paths (alternately you could
       have changed the paths via options to `configure'.

    5) Type `make' to compile sudo.  If you are building sudo
       in a separate build tree (apart from the sudo source)
       GNU make will probably be required.  If `configure' did
       its job properly (and you have a supported configuration)
       there won't be any problems.  If this doesn't work, take
       a look at the files TROUBLESHOOTING and PORTING for tips
       on what might have gone wrong.  Please mail us if you have a
       fix or if you are unable to come up with a fix (address at EOF).

    6) Type `make install' (as root) to install sudo, visudo, the
       man pages, and a skeleton sudoers file.  Note that the install
       will not overwrite an existing sudoers file.  You can also
       install various pieces the package via the install-binaries,
       install-man, and install-sudoers make targets.

    7) Edit the sudoers file with `visudo' as necessary for your
       site.  You will probably want to refer the sample.sudoers
       file and sudoers man page included with the sudo package.

    8) If you want to use syslogd(8) to do the logging, you'll need
       to update your /etc/syslog.conf file.  See the sample.syslog.conf
       file included in the distribution for an example.

Available configure options
===========================

This section describes flags accepted by the sudo's `configure' script.
Defaults are listed in brackets after the description.

Configuration:
  --cache-file=FILE
	Cache test results in FILE

  --config-cache, -C
	Alias for `--cache-file=config.cache'

  --help, -h
	Print the usage/help info

  --no-create, -n
	Do not create output files

  --quiet, --silent, -q
	Do not print `checking...' messages

Directory and file names:
  --prefix=PREFIX
	Install architecture-independent files in PREFIX This really only
	applies to man pages.  [/usr/local]

  --exec-prefix=EPREFIX
	Install architecture-dependent files in EPREFIX This includes the
	sudo and visudo executables.  [same as prefix]

  --bindir=DIR
	Install `sudo' in DIR [EPREFIX/bin]

  --sbindir=DIR
	Install `visudo' in DIR [EPREFIX/sbin]

  --sysconfdir=DIR
	Install `sudoers' file in DIR [/etc]

  --mandir=DIR
	Install man pages in DIR [PREFIX/man]

  --srcdir=DIR
	Find the sources in DIR [configure dir or ..]

Special features/options:
  --with-CC=PATH
	Specifies path to C compiler you wish to use.

  --with-incpath=DIR
        Adds the specified directory (or directories) to CPPFLAGS
        so configure and the compiler will look there for include
        files.  Multiple directories may be specified as long as
        they are space separated.
	Eg: --with-incpath="/usr/local/include /opt/include"

  --with-libpath=DIR
        Adds the specified directory (or directories) to LDFLAGS
        so configure and the compiler will look there for libraries.
        Multiple directories may be specified as with --with-incpath.

  --with-rpath
	Tells configure to use -Rpath in addition to -Lpath when
	passing library paths to the loader.  This option is on
	by default for Solaris and SVR4.

  --with-blibpath[=PATH]
        Tells configure to construct a -blibpath argument to the
        loader.  If a PATH is specified, it will be used as the
        base.  Otherwise, "/usr/lib:/lib:/usr/local/lib" will be
        used for gcc and "/usr/lib:/lib" for non-gcc.  Additional
        library paths will be appended as needed by configure.
	This option is only valid for AIX where it is on by default.

  --with-libraries=LIBRARY
        Adds the specified library (or libaries) to SUDO_LIBS and
        and VISUDO_LIBS so sudo will link against them.  If the
        library doesn't start with `-l' or end in `.a' or `.o' a
        `-l' will be prepended to it.  Multiple libraries may be
        specified as long as they are space separated.

  --with-csops
	Add CSOps standard options.  You probably aren't interested in this.

  --with-skey[=DIR]
        Enable S/Key OTP (One Time Password) support.  If specified,
        DIR should contain include and lib directories with skey.h
        and libskey.a respectively.

  --with-opie[=DIR]
	Enable NRL OPIE OTP (One Time Password) support.  If specified,
	DIR should contain include and lib directories with opie.h
	and libopie.a respectively.

  --with-SecurID[=DIR]
	Enable SecurID support.  If specified, DIR is directory containing
	sdiclient.a, sdi_athd.h, sdconf.h, and sdacmvls.h.

  --with-fwtk[=DIR]
	Enable TIS Firewall Toolkit (FWTK) 'authsrv' support. If specified,
	DIR is the base directory containing the compiled FWTK package
	(or at least the library and header files).

  --with-kerb4[=DIR]
        Enable Kerberos IV support.  If specified, DIR is the base
        directory containing the Kerberos IV include and lib dirs.
        This uses Kerberos passphrases for authentication but does
        not use the Kerberos cookie scheme.

  --with-kerb5[=DIR]
        Enable Kerberos V support.  If specified, DIR is the base
        directory containing the Kerberos V include and lib dirs.
        This This uses Kerberos passphrases for authentication but
        does not use the Kerberos cookie scheme.  Will not work for
        Kerberos V older than version 1.1.

  --with-authenticate
	Enable support for the AIX 4.x general authentication function.
	This will use the authentication scheme specified for the user
	on the machine.

  --with-pam
	Enable PAM support.  Tested on:
	    Redhat Linux 5.x, 6.0, and 6.1
	    Solaris 2.6 and 7
	    HP-UX 11.0
        NOTE: on RedHat Linux you *must* install an /etc/pam.d/sudo file.
	You may either use the sample.pam file included with sudo or use
	/etc/pam.d/su as a reference.  On Solaris and HP-UX 11 systems
	you should check (and understand) the contents of /etc/pam.conf.
	Do a "man pam.conf" for more information and consider using the
	"debug" option, if available, with your PAM libraries in
	/etc/pam.conf to obtain syslog output for debugging purposes.

  --with-AFS
	Enable AFS support with Kerberos authentication.  Should work under
	AFS 3.3.  If your AFS doesn't have -laudit you should be able to
	link without it.

  --with-DCE
	Enable DCE support.  Known to work on HP-UX 9.X, 10.X, and 11.0.
	The use of PAM is recommended for HP-UX 11.X systems, since PAM is
	fully implemented (this is not true for 10.20 and earlier versions).
	Check to see that your 11.X (or other) system uses DCE via PAM by
	looking at /etc/pam.conf to see if "libpam_dce" libraries are 
	referenced there.  Other platforms may require source code and/or 
	`configure' changes; you should check to see if your platform can 
	access DCE via PAM before using this option.

  --with-logincap
	Enable support for BSD login classes where available (OS-dependent).
	This adds support for the login classes specified in /etc/login.conf.
	By default, a login class is not applied unless the 'use_loginclass'
	option is defined in sudoers or the user specifies a class on the
	command line.

  --with-bsdauth
        Enable support for BSD authentication on BSD/OS and OpenBSD.
        This option implies --with-logincap.  It is not possible
        to mix BSD authentication with other authentication methods
        (and there really should be no need to do so).  Note that
        only the newer BSD authentication API is supported.  If you
        don't have /usr/include/bsd_auth.h then you cannot use this.

  --disable-root-mailer
        By default sudo will run the mailer as root when tattling
        on a user so as to prevent that user from killing the mailer.
        With this option, sudo will run the mailer as the invoking
        user which some people consider to be safer.

  --disable-saved-ids
        Disable use of POSIX saved IDs.  Normally, sudo will try
        to use POSIX saved IDs if they are supported.  However,
        some implementations are broken.

  --disable-setreuid
        Disable use of the setreuid() function for operating systems
        where it is broken.  4.4BSD has setreuid() but it doesn't
        really work.

  --disable-setresuid
        Disable use of the setresuid() function for operating systems
        where it is broken (none currently known).

  --disable-sia
        Disable SIA support.  This is the "Security Integration
        Architecture" on Digital UNIX. If you disable SIA sudo will
        use its own authentication routines.

  --disable-shadow
        Disable shadow password support.  Normally, sudo will compile
        in shadow password support and use a shadow password if it
        exists.

  --with-sudoers-mode=MODE
        File mode for the sudoers file (octal).  Note that if you
        wish to NFS-mount the sudoers file this must be group
        readable.  Also note that this is actually set in the
        Makefile.  The default mode is 0440.

  --with-sudoers-uid=UID
        User id that "owns" the sudoers file.  Note that this is
        the numeric id, *not* the symbolic name.  Also note that
        this is actually set in the Makefile.  The default is 0.

  --with-sudoers-gid=GID
        Group id that "owns" the sudoers file.  Note that this is
        the numeric id, *not* the symbolic name.  Also note that
        this is actually set in the Makefile.  The default is 0.

  --with-execv
	Use execv() to exec the command instead of execvp().  I can't think of
	a reason to actually do this since execvp() is passed a fully qualified
	pathname but someone might thoroughly distrust execvp().  Note that if
	you define this you lose the ability to exec scripts that are missing
	the '#!/bin/sh' cookie (like /bin/kill on SunOS and /etc/fastboot on
	4.3BSD).  This is off by default.

  --without-interfaces
        This option keeps sudo from trying to glean the ip address
        from each attached ethernet interface.  It is only useful
        on a machine where sudo's interface reading support does
        not work, which may be the case on some SysV-based OS's
        using STREAMS.

  --without-passwd
        This option excludes authentication via the passwd (or
        shadow) file.  It should only be used when another, alternate,
        authentication scheme is in use.

  --with-otp-only
        This option is now just an alias for --without-passwd.

  --with-stow
        Properly handle GNU stow packaging.  The sudoers file will
        physically live in ${prefix}/etc and /etc/sudoers will be
        a symbolic link.

The following options are also configurable at runtime:

  --with-long-otp-prompt
        When validating with a One Time Password scheme (S/Key or
        OPIE), a two-line prompt is used to make it easier to cut
        and paste the challenge to a local window.  It's not as
        pretty as the default but some people find it more convenient.

  --with-logging=TYPE
        How you want to do your logging.  You may choose "syslog",
        "file", or "both".  Setting this to "syslog" is nice because
        you can keep all of your sudo logs in one place (see the
        sample.syslog.conf file).  The default is "syslog".

  --with-logfac=FACILITY
        Determines which syslog facility to log to.  This requires
        a 4.3BSD or later version of syslog.  You can still set
        this for ancient syslogs but it will have no effect.  The
        following facilities are supported: authpriv (if your OS
        supports it), auth, daemon, user, local0, local1, local2,
        local3, local4, local5, local6, and local7.

  --with-goodpri=PRIORITY
        Determines which syslog priority to log successfully
        authenticated commands.  The following priorities are
        supported: alert, crit, debug, emerg, err, info, notice,
        and warning.

  --with-badpri=PRIORITY
        Determines which syslog priority to log unauthenticated
        commands and errors.  The following priorities are supported:
        alert, crit, debug, emerg, err, info, notice, and warning.

  --with-logpath=PATH
        Override the default location of the sudo log file and use
        "path" instead.  By default will use /var/log/sudo.log if
        there is a /var/log dir, falling back to /var/adm/sudo.log
        or /usr/adm/sudo.log if not.

  --with-loglen=NUMBER
	Number of characters per line for the file log.  This is only used if
	you are to "file" or "both".  This value is used to decide when to wrap
	lines for nicer log files.  The default is 80.  Setting this to 0
	will disable the wrapping.

  --with-ignore-dot
	If set, sudo will ignore '.' or '' (current dir) in $PATH.
	The $PATH itself is not modified.

  --with-mailto=USER|MAIL_ALIAS
	User (or mail alias) that mail from sudo is sent to.
	This should go to a sysadmin at your site.  The default is "root".

  --with-mailsubject="SUBJECT OF MAIL"
	Subject of the mail sent to the "mailto" user. The token "%h"
	will expand to the hostname of the machine.
	Default is "*** SECURITY information for %h ***".

  --without-mail-if-no-user
	Normally, sudo will mail to the "alertmail" user if the user invoking
	sudo is not in the sudoers file.  This option disables that behavior.

  --with-mail-if-no-host
	Send mail to the "alermail" user if the user exists in the sudoers
	file, but is not allowed to run commands on the current host.

  --with-mail-if-noperms
	Send mail to the "alermail" user if the user is allowed to use sudo but
	the command they are trying is not listed in their sudoers file entry.

  --with-passprompt="PASSWORD PROMPT"
	Default prompt to use when asking for a password; can be overridden
	via the -p option and the SUDO_PROMPT environment variable. Supports
	two escapes: "%u" expands to the user's login name and "%h" expands
	to the local hostname.  Default is "Password:".

  --with-badpass-message="BAD PASSWORD MESSAGE"
	Message that is displayed if a user enters an incorrect password.
	The default is "Sorry, try again." unless insults are turned on.

  --with-fqdn
        Define this if you want to put fully qualified hostnames in the sudoers
	file.  Ie: instead of myhost you would use myhost.mydomain.edu.  You may
	still use the short form if you wish (and even mix the two).  Beware
	that turning FQDN on requires sudo to make DNS lookups which may make
	sudo unusable if your DNS is totally hosed.  Also note that you must
	use the host's official name as DNS knows it.  That is, you may not use
	a host alias (CNAME entry) due to performance issues and the fact that
	there is no way to get all aliases from DNS.

  --with-timedir=PATH
	Override the default location of the sudo timestamp directory and
	use "path" instead.

  --with-sendmail=PATH
	Override configure's guess as to the location of sendmail.

  --without-sendmail
	Do not use sendmail to mail messages to the "mailto" user.
	Use only if don't run sendmail or the equivalent.

  --with-umask=MASK
	Umask to use when running the root command.  The default is 0022.

  --without-umask
	Preserves the umask of the user invoking sudo.

  --with-runas-default=USER
	The default user to run commands as if the -u flag is not specified
	on the command line.  This defaults to "root".

  --with-exempt=GROUP
	Users in the specified group don't need to enter a password when
	running sudo.  This may be useful for sites that don't want their
	"core" sysadmins to have to enter a password but where Jr. sysadmins
	need to.  You should probably use NOPASSWD in sudoers instead.

  --with-passwd-tries=NUMBER
	Number of tries a user gets to enter his/her password before sudo logs
	the failure and exits.  The default is 3.

  --with-timeout=NUMBER
	Number of minutes that can elapse before sudo will ask for a passwd
	again.  The default is 5, set this to 0 to always prompt for a password.

  --with-password-timeout=NUMBER
	Number of minutes before the sudo password prompt times out.
	The default is 5, set this to 0 for no password timeout.

  --with-tty-tickets
	This makes sudo use a different ticket file for each user/tty combo.
	Ie: instead of the ticket path being "username" it is "username/tty".
	This is useful for "shared" accounts like "operator".  Note that this
	means that there will be more files in the timestamp dir.  This is not
	a problem if your system has a cron job to remove of files from /tmp
	(or wherever you specified the timestamp dir to be).

  --with-insults
	Define this if you want to be insulted for typing an incorrect password
	just like the original sudo(8).  This is off by default.

  --with-all-insults
	Include all the insult sets listed below.  You must either specify
	--with-insults or enable insults in the sudoers file for this to
	have any effect.

  --with-classic-insults
	Uses insults from sudo "classic."  If you just specify --with-insults
	you will get the classic and CSOps insults.  This is on by default if
	--with-insults is given.

  --with-csops-insults
	Insults the user with an extra set of insults (some quotes, some
	original) from a sysadmin group at CU (CSOps).  You must specify
	--with-insults as well for this to have any effect.  This is on by
	default if --with-insults is given.

  --with-hal-insults
	Uses 2001-like insults when an incorrect password is entered.
	You must either specify --with-insults or enable insults in the
	sudoers file for this to have any effect.

  --with-goons-insults
	Insults the user with lines from the "Goon Show" when an incorrect
	password is entered.  You must either specify --with-insults or
	enable insults in the sudoers file for this to have any effect.

  --with-secure-path[=PATH]
	Path used for every command run from sudo(8).  If you don't trust the
	people running sudo to have a sane PATH environment variable you may
	want to use this.  Another use is if you want to have the "root path"
	be separate from the "user path."  You will need to customize the path
	for your site.  NOTE: this is not applied to users in the group
	specified by --with-exemptgroup.  If you do not specify a path,
	"/bin:/usr/ucb:/usr/bin:/usr/sbin:/sbin:/usr/etc:/etc" is used.

  --without-lecture
	Don't print the lecture the first time a user runs sudo.

  --with-editor=PATH
	Specify the default editor path for use by visudo.  This may be
	a single pathname or a colon-separated list of editors.  In
	the latter case, visudo will choose the editor that matches
	the user's USER environment variable or the first editor in
	the list that exists.  The default is the path to vi on your system.

  --with-env-editor
	Makes visudo consult the EDITOR and VISUAL environment variables before
	falling back on the default editor list (as specified by --with-editor).
	Note that this may create a security hole as it allows the user to
	run any arbitrary command as root without logging.  A safer alternative
	is to use a colon-separated list of editors with the --with-env-editor
	option.  visudo will then only use the EDITOR or VISUAL if they match
	a value specified via --with-editor.

  --disable-authentication
        By default, sudo requires the user to authenticate via a
        password or similar means.  This options causes sudo to
        *not* require authentication.  It is possible to turn
        authentication back on in sudoers via the PASSWD attribute.

  --disable-root-sudo
	Don't let root run sudo.  This can be used to prevent people from
	"chaining" sudo commands to get a root shell by doing something
	like "sudo sudo /bin/sh".

  --enable-log-host
	Log the hostname in the log file.

  --enable-noargs-shell
	If sudo is invoked with no arguments it acts as if the "-s" flag had
	been given.  That is, it runs a shell as root (the shell is determined
	by the SHELL environment variable, falling back on the shell listed
	in the invoking user's /etc/passwd entry).

  --enable-shell-sets-home
	If sudo is invoked with the "-s" flag the HOME environment variable
	will be set to the home directory of the target user (which is root
	unless the "-u" option is used).  This option effectively makes the
	"-s" flag imply "-H".

  --disable-path-info
	Normally, sudo will tell the user when a command could not be found
	in their $PATH.  Some sites may wish to disable this as it could
	be used to gather information on the location of executables that
	the normal user does not have access to.  The disadvantage is that
	if the executable is simply not in the user's path, sudo will tell
	the user that they are not allowed to run it, which can be confusing.

Shadow password and C2 support
==============================

Shadow passwords (also included with most C2 security packages) are
supported on most major platforms for which they exist.  The
`configure' script will attempt to determine if your system can use
shadow passwords and include support for them if so.  Shadow password
support is now compiled in by default (it doesn't hurt anything if you
don't have them configured).  To disable the shadow password support,
use the --disable-shadow option to configure.

Shadow passwords are known to work on the following platforms:

    SunOS 4.x
    Solaris 2.x
    HP-UX >= 9.x
    Ultrix 4.x
    Digital UNIX
    IRIX >= 5.x
    AIX >= 3.2.x
    ConvexOS with C2 security (not tested recently)
    Linux
    SCO >= 3.2.2
    Pyramid DC/OSx
    UnixWare
    SVR4 (and variants using standard SVR4 shadow passwords)
    4.4BSD based systems (including OpenBSD, NetBSD, FreeBSD, and BSD/OS)
    OS's using SecureWare's C2 security.

OS dependent notes
==================

OpenBSD < 2.2 and NetBSD < 1.2.1:
    The fdesc filesystem has a bug wrt /dev/tty handling that
    causes sudo to hang at the password prompt.  The workaround
    is to run configure with --with-password-timeout=0

Solaris 2.x:
    You need to have a C compiler in order to build sudo.
    Since Solaris 2.x does not come with one by default this
    means that you either need to have purchased the unbundled Sun
    C compiler or have a copy of the GNU C compiler (gcc).
    The SunSoft Catalyst CD should contain gcc binaries for
    Solaris.  You can also get them from various places on the
    net, including http://www.sunfreeware.com/
    NOTE: sudo will *not* build with the sun C compiler in BSD
          compatibility mode (/usr/ucb/cc).  Sudo is designed to
          compile with the standard C compiler (or gcc) and will
          not build correctly with /usr/ucb/cc.  You can use the
          `--with-CC' option to point `configure' to the non-ucb
          compiler if it is not the first cc in your path.  Some
          sites link /usr/ucb/cc to gcc; configure will not notice
          this an still refuse to use /usr/ucb/cc, so make sure gcc
          is also in your path if your site is setup this way.
    Also: Many versions of Solaris come with a broken syslogd.
	  If you have having problems with sudo logging you should
	  make sure you have the latest syslogd patch installed.
	  This is a problem for Solaris 2.4 and 2.5 at least.

AIX 3.2.x:
    I've had various problems with the AIX C compiler producing
    incorrect code when the -O flag was used.  When optimization
    is not used, the problems go away.  Gcc does not appear
    to have this problem.

    Also, the AIX 3.2.x lex will not work with sudo's parse.lex.
    This should not be a problem as sudo comes shipped with
    a pre-generated lex.yy.c (created by flex).  If you want
    to modify the lex tokenizer, make sure you grab a copy of
    flex from ftp.ee.lbl.gov (also available on most GNU mirrors)
    and sudo will use that instead.

Ultrix 4.x:
    Ultrix still ships with the 4.2BSD syslog(3) which does not
    allow things like logging different facilities to different
    files, redirecting logs to a single loghost and other niceties.
    You may want to just grab and install:
	ftp://gatekeeper.dec.com/pub/DEC/jtkohl-syslog-complete.tar.Z
    (available via anonymous ftp) which is a port if the 4.3BSD
    syslog/syslogd that is backwards compatible with the Ultrix version.
    I recommend it highly.  If you do not do this you probably want
    to run configure with --with-logging=file

Digital UNIX:
    By default, sudo will use SIA (Security Integration Architecture)
    to validate a user.  If you want to use an alternate authentication
    method that does not go through SIA, you need to use the
    --disable-sia option to configure.  If you use gcc to compile
    you will get warnings when building interfaces.c.  These are
    harmless but if they really bug you, you can edit
    /usr/include/net/if.h around line 123, right after the comment:
	/* forward decls for C++ */
    change the line:
	#ifdef __cplusplus
    to:
	#if defined(__cplusplus) || defined(__GNUC__)
    If you don't like the idea of editing the system header file
    you can just make a copy in gcc's private include tree and
    edit that.

Linux:
    NOTE: Reportedly, Linux's execvp(3) doesn't always execute
	  scripts that lack the "#!/some/shell" header correctly.
	  The workaround is to give all your scripts a proper
	  header.
    Versions of glibc 2.x previous to 2.0.7 have a broken lsearch().
    You will need to either upgrade to glibc-2.0.7 or use sudo's
    version of lsearch().  To use sudo's lsearch(), comment out
    the "#define HAVE_LSEARCH 1" line in config.h and add lsearch.o
    to the LIBOBJS line in the Makefile.

    If you are using a Linux kernel older than 2.4 it is not possible
    to access the sudoers file via NFS.  This is due to a bug in
    the Linux client-side NFS implementation that has since been
    fixed.  There is a workaround on the sudo ftp site, linux_nfs.patch,
    if you need to NFS-mount sudoers on older Linux kernels.

    Linux kernels 2.2.16-2.2.19 appear to have broken POSIX saved
    ID support.  You must run configure with the --disable-saved-ids
    flag to get a working sudo.

Mac OS X:
    It has been reported that for sudo to work on Mac OS X it must
    either be built with the --with-password-timeout=0 option or the
    password timeout must be disabled in the Defaults line in the
    sudoers file.  If sudo just hangs when you try to enter a password,
    you need to disable the password timeout (Note: this is not a bug
    in sudo).

SCO ODT:
    You'll probably need libcrypt_i.a available via anonymous ftp
    from sosco.sco.com.  The necessary files are /SLS/lng225b.Z
    and /SLS/lng225b.ltr.Z.

Dynix:
    Some people have experienced problems building sudo with gcc
    on Dynix.  If you experience problems compiling sudo using gcc
    on Dynix, try using the native compiler (cc).  You can do so
    by removing the config.cache file and then re-running configure
    with the --with-CC=cc option.