NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON
MKSTEMP(3) Linux Programmer's Manual MKSTEMP(3)
mkstemp, mkostemp - create a unique temporary file
#include <stdlib.h>
int mkstemp(char *template);
int mkostemp (char *template, int flags);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
mkstemp(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500
mkostemp(): _GNU_SOURCE
The mkstemp() function generates a unique temporary filename from template,
creates and opens the file, and returns an open file descriptor for the file.
The last six characters of template must be "XXXXXX" and these are replaced
with a string that makes the filename unique. Since it will be modified,
template must not be a string constant, but should be declared as a character
array.
The file is created with permissions 0600, that is, read plus write for owner
only. (In glibc versions 2.06 and earlier, the file is created with
permissions 0666, that is, read and write for all users.) The returned file
descriptor provides both read and write access to the file. The file is
opened with the open(2) O_EXCL flag, guaranteeing that the caller is the
process that creates the file.
mkostemp() is like mkstemp(), with the difference that flags as for open(2)
may be specified in flags (e.g., O_APPEND, O_SYNC).
On success, these functions return the file descriptor of the temporary file.
On error, -1 is returned, and errno is set appropriately.
EEXIST Could not create a unique temporary filename. Now the contents of
template are undefined.
EINVAL The last six characters of template were not XXXXXX. Now template is
unchanged.
These functions may also fail with any of the errors described for open(2).
mkostemp() is available since glibc 2.7.
mkstemp(): 4.3BSD, POSIX.1-2001. mkostemp(): is a glibc extension.
The old behavior of creating a file with mode 0666 may be a security risk,
especially since other Unix flavors use 0600, and somebody might overlook this
detail when porting programs.
More generally, the POSIX specification of mkstemp() does not say anything
about file modes, so the application should make sure its file mode creation
mask (see umask(2)) is set appropriately before calling mkstemp() (and
mkostemp()).
The prototype for mktemp() is in <unistd.h> for libc4, libc5, glibc1; glibc2
follows POSIX.1 and has the prototype in <stdlib.h>.
mkdtemp(3), mktemp(3), tempnam(3), tmpfile(3), tmpnam(3)
This page is part of release 3.11 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
GNU 2008-06-19 MKSTEMP(3)