usr/src/lib/libc/stdio/mktemp.3

.\" Copyright (c) 1989 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" %sccs.include.redist.man%
.\"
.\"     @(#)mktemp.3    6.8 (Berkeley) %G%
.\"
.TH MKTEMP 3  ""
.AT 3
.SH NAME
mktemp \- create a unique file name
.SH SYNOPSIS
.nf
.ft B
#include <unistd.h>

char *mktemp(char *template);

int mkstemp(char *template);
.ft R
.fi
.SH DESCRIPTION
.I Mktemp
takes a file name template and overwrites it to create a unique file
name for use by the application.
The template may be any file name with some number of X's appended
to it, for example ``/tmp/temp.XXXX''.
The trailing X's are replaced with the current process number and/or a
unique letter combination.
The number of unique file names
.I mktemp
can return depends on the number of X's provided; six X's will
result in
.I mktemp
testing roughly 26 ** 6 combinations.
.PP
.I Mkstemp
makes the same replacement to the template and creates the template file,
mode 0600, returning a file descriptor opened for reading and writing.
This avoids the race between testing for a file's existence and opening it
for use.
.SH "RETURN VALUE"
.I Mktemp
returns a pointer to the template on success and NULL on failure.
.I Mkstemp
returns -1 if no suitable file could be created.
If either call fails an error code is placed in the global location
.IR errno .
.SH ERRORS
.I Mktemp
and
.I mkstemp
may set
.I errno
to one of the following values:
.TP
[ENOTDIR]
The pathname portion of the template is not an existing directory.
.PP
.I Mktemp
and
.I mkstemp
may also set
.I errno
to any value specified by the
.IR stat (2)
function.
.I Mkstemp
may also set
.I errno
to any value specified by the
.IR open (2)
function.
.SH "SEE ALSO"
chmod(2), getpid(2), open(2), stat(2)