.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
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.\" manual provided the copyright notice and this permission notice are
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.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
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.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sat Jul 24 18:48:48 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified 980310, aeb
.\" Modified 990328, aeb
.\"
.TH MKSTEMP 3  "April 3, 1993" "GNU" "Linux Programmer's Manual"
.SH NAME
mkstemp \- create a unique temporary file
.SH SYNOPSIS
.nf
.B #include <stdlib.h>
.sp
.BI "int mkstemp(char *" template );
.fi
.SH DESCRIPTION
The \fBmkstemp()\fP function generates a unique temporary file name
from \fItemplate\fP.  The last six characters of \fItemplate\fP must
be XXXXXX and these are replaced with a string that makes the
filename unique. The file is then created with mode read/write and
permissions 0666 (glibc 2.0.6 and earlier), 0600 (glibc 2.0.7 and later).
Since it will be modified,
.I template
must not be a string constant, but should be declared as a character array.
The file is opened with the O_EXCL flag, guaranteeing that when
.B mkstemp
returns successfully we are the only user.
.SH "RETURN VALUE"
The \fBmkstemp()\fP function returns the file descriptor fd of the
temporary file or \-1 on error.
.SH "ERRORS"
.TP
.B EINVAL
The last six characters of \fItemplate\fP were not XXXXXX.
Now \fItemplate\fP is unchanged.
.TP
.B EEXIST
Could not create a unique temporary filename.
Now the contents of \fItemplate\fP are undefined.
.SH BUGS
The old behaviour (creating a file with mode 0666) may be
a security risk, especially since other Unix flavours use 0600,
and somebody might overlook this detail when porting programs.
.SH "CONFORMING TO"
BSD 4.3
.SH NOTE
The prototype is in
.I <unistd.h>
for libc4, libc5, glibc1; glibc2 follows the Single Unix Specification
and has the prototype in
.IR <stdlib.h> .
.SH "SEE ALSO"
.BR mktemp "(3), " tmpnam "(3), " tempnam "(3), " tmpfile (3)