mktemp(1)							   User Commands							 mktemp(1)

NAME

       mktemp - make temporary filename

SYNOPSIS

       mktemp [-dtqu] [-p directory] [template]

DESCRIPTION

       The  mktemp  utility  makes a temporay filename. To do this, mktemp takes the specified filename template and overwrites a portion of it to
       create a unique filename. See OPERANDS.

       The template is passed to mktemp(3C) for directories or mkstemp(3C) for ordinary files.

       If mktemp can successfully generate a unique filename, the file (or directory) is created with file permissions such that it is only  read-
       able and writable by its owner (unless the -u flag is given) and the filename is printed to standard output.

       mktemp allows shell scripts to safely use temporary files. Traditionally, many shell scripts take the name of the program with the PID as a
       suffix and used that as a temporary filename. 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 guaran-
       tees that a temporary file is not subverted, it still allows a simple denial of service attack. Use mktemp instead.

OPTIONS

       The following options are supported:

       -d		       Make a directory instead of a file.

       -p directory	       Use the specified directory as a prefix when generating the temporary filename. The directory is overridden by  the
			       user's TMPDIR environment variable if it is set.This option implies the -t flag.

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

       -t		       Generate a path rooted in a temporary directory. This directory is chosen as follows: If the user's TMPDIR environ-
			       ment variable is set, the directory contained therein is used. Otherwise, if the -p flag was  given  the  specified
			       directory  is used. If none of the above apply, /tmp is used. In this mode, the template (if specified) should be a
			       directory component (as opposed to a full path) and thus should not contain any forward slashes.

       -u			Operate in unsafe mode. The temp file is unlinked before mktemp exits. This is slightly  better  than  mktemp(3C),
			       but still introduces a race condition. Use of this option is discouraged.

OPERANDS

       The following operands are supported:

       template 	       template can be any filename with one or more Xs appended to it, for example /tmp/tfile.XXXXXX.

			       If template is not specified, a default of tmp.XXXXXX is used and the -t flag is implied.

EXAMPLES

       Example 1: Using mktemp

       The  following example illustrates a simple use of mktemp in a sh(1) script. In this example, the script quits if it cannot get a safe tem-
       porary file.

       TMPFILE=`mktemp /tmp/example.XXXXXX`
       if [ -z "$TMPFILE" ]; then exit 1; fi
       echo "program output" >> $TMPFILE

       Example 2: Using mktemp to Support TMPDIR

       The following example uses mktemp to support for a user's TMPDIR environment variable:

       TMPFILE=`mktemp -t example.XXXXXX`
       if [ -z "$TMPFILE" ]; then exit 1; fi
       echo "program output" >> $TMPFILE

       Example 3: Using mktemp Without Specifying the Name of the Temporary File

       The following example uses mktemp without specifying the name of the temporary file. In this case the -t flag is implied.

       TMPFILE=`mktemp`
       if [ -z "$TMPFILE" ]; then exit 1; fi
       echo "program output" >> $TMPFILE

       Example 4: Using mktemp with a Default Temporary Directory Other than /tmp

       The following example creates the temporary file in /extra/tmp unless the user's TMPDIR environment variable specifies otherwise:

       TMPFILE=`mktemp -p /extra/tmp example.XXXXX`
       if [ -z "$TMPFILE" ]; then exit 1; fi
       echo "program output" >> $TMPFILE

       Example 5: Using mktemp to Remove a File

       The following example attempts to create two temporary files. If creation of the second temporary file fails, mktemp removes the first file
       before exiting:

       TMP1=`mktemp -t example.1.XXXXXX`
       if [ -z "$TMP1" ]; then exit 1; fi
       TMP2=`mktemp -t example.2.XXXXXX`
       if [ -z "$TMP2" ]; then
	       rm -f $TMP1
	       exit 1
       fi

       Example 6: Using mktemp

       The following example does not exit if mktemp is unable to create the file. That part of the script has been protected.

       TMPFILE=`mktemp -q -t example.XXXXXX`
       if [ ! -z "$TMPFILE" ]
       then
	       # Safe to use $TMPFILE in this block
	       echo data > $TMPFILE
	       ...
	       rm -f $TMPFILE
       fi

ENVIRONMENT VARIABLES

       See environ(5) for descriptions of the following environment variables that affect the execution of mktemp with the -t option: TMPDIR.

EXIT STATUS

       The following exit values are returned:

       0	Successful completion.

       1	An error occurred.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       sh(1), mkstemp(3C), mktemp(3C), attributes(5), environ(5)

NOTES

       The  mktemp  utility  appeared  in  OpenBSD  2.1.  The  Solaris implementation uses only as many `Xs' as are significant for mktemp(3C) and
       mkstemp(3C).

SunOS 5.10							    4 Jun 2004								 mktemp(1)