MKSTEMP(3P) POSIX Programmer's Manual MKSTEMP(3P)
PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond-
ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
NAME
mkstemp - make a unique filename
SYNOPSIS
#include <stdlib.h>
int mkstemp(char *template);
DESCRIPTION
The mkstemp() function shall replace the contents of the string pointed to by template by a unique filename, and return a file descriptor
for the file open for reading and writing. The function thus prevents any possible race condition between testing whether the file exists
and opening it for use. The string in template should look like a filename with six trailing 'X' s; mkstemp() replaces each 'X' with a
character from the portable filename character set. The characters are chosen such that the resulting name does not duplicate the name of
an existing file at the time of a call to mkstemp().
RETURN VALUE
Upon successful completion, mkstemp() shall return an open file descriptor. Otherwise, -1 shall be returned if no suitable file could be
created.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
Generating a Filename
The following example creates a file with a 10-character name beginning with the characters "file" and opens the file for reading and writ-
ing. The value returned as the value of fd is a file descriptor that identifies the file.
#include <stdlib.h>
...
char template[] = "/tmp/fileXXXXXX";
int fd;
fd = mkstemp(template);
APPLICATION USAGE
It is possible to run out of letters.
The mkstemp() function need not check to determine whether the filename part of template exceeds the maximum allowable filename length.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
getpid(), open(), tmpfile(), tmpnam(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdlib.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
online at http://www.opengroup.org/unix/online.html .
IEEE
/The Open Group 2003 MKSTEMP(3P)