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OpenDarwin 7.2.1 - man page for mktemp (opendarwin section 1)

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MKTEMP(1)			   BSD General Commands Manual				MKTEMP(1)

NAME
     mktemp -- make temporary file name (unique)

SYNOPSIS
     mktemp [-d] [-q] [-t prefix] [-u] template ...
     mktemp [-d] [-q] [-u] -t prefix

DESCRIPTION
     The mktemp utility takes each of the given file name templates and overwrites a portion of
     it to create a file name.	This file name is unique and suitable for use by the application.
     The template may be any file name with some number of 'Xs' appended to it, for example
     /tmp/temp.XXXX.  The trailing 'Xs' are replaced with the current process number and/or a
     unique letter combination.  The number of unique file names mktemp can return depends on the
     number of 'Xs' provided; six 'Xs' will result in mktemp testing roughly 26 ** 6 combina-
     tions.

     If mktemp can successfully generate a unique file name, the file is created with mode 0600
     (unless the -u flag is given) and the filename is printed to standard output.

     If the -t prefix option is given, mktemp will generate an template string based on the
     prefix and the TMPDIR environment variable if set.  The default location if TMPDIR is not
     set is /tmp.  Care should be taken to ensure that it is appropriate to use an environment
     variable potentially supplied by the user.

     Any number of temporary files may be created in a single invocation, including one based on
     the internal template resulting from the -t flag.

     Mktemp is provided to allow shell scripts to safely use temporary files.  Traditionally,
     many shell scripts take the name of the program with the pid as a suffix and use that as a
     temporary file name.  This kind of naming scheme is predictable and the race condition it
     creates is easy for an attacker to win.  A safer, though still inferior, approach is to make
     a temporary directory using the same naming scheme.  While this does allow one to guarantee
     that a temporary file will not be subverted, it still allows a simple denial of service
     attack.  For these reasons it is suggested that mktemp be used instead.

OPTIONS
     The available options are as follows:

     -d      Make a directory instead of a file.

     -q      Fail silently if an error occurs.	This is useful if a script does not want error
	     output to go to standard error.

     -t prefix
	     Generate a template (using the supplied prefix and TMPDIR if set) to create a file-
	     name template.

     -u      Operate in ``unsafe'' mode.  The temp file will be unlinked before mktemp exits.
	     This is slightly better than mktemp(3) but still introduces a race condition.  Use
	     of this option is not encouraged.

DIAGNOSTICS
     The mktemp utility exits 0 on success, and 1 if an error occurs.

EXAMPLES
     The following sh(1) fragment illustrates a simple use of mktemp where the script should quit
     if it cannot get a safe temporary file.

	   tempfoo=`basename $0`
	   TMPFILE=`mktemp /tmp/${tempfoo}.XXXXXX` || exit 1
	   echo "program output" >> $TMPFILE

     To allow the use of $TMPDIR:

	   tempfoo=`basename $0`
	   TMPFILE=`mktemp -t ${tempfoo}` || exit 1
	   echo "program output" >> $TMPFILE

     In this case, we want the script to catch the error itself.

	   tempfoo=`basename $0`
	   TMPFILE=`mktemp -q /tmp/${tempfoo}.XXXXXX`
	   if [ $? -ne 0 ]; then
		   echo "$0: Can't create temp file, exiting..."
		   exit 1
	   fi

SEE ALSO
     mkdtemp(3), mkstemp(3), mktemp(3), environ(7)

HISTORY
     A mktemp utility appeared in OpenBSD 2.1.	This implementation was written independently
     based on the OpenBSD man page, and first appeared in FreeBSD 2.2.7.  This man page is taken
     from OpenBSD

BSD					November 20, 1996				      BSD
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