NAME
mkstemp - create a unique temporary file
SYNOPSIS
#include <stdlib.h>
I int mkstemp(char * template );
DESCRIPTION
The
R mkstemp ()
function generates a unique temporary filename
from
template.
The last six characters of
template 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,
template
must not be a string constant, but should be declared as a character array.
The file is opened with the
open(2)
O_EXCL
flag, guaranteeing that when
R mkstemp ()
returns successfully we are the only user.
RETURN VALUE
On success, the
R mkstemp ()
function returns the file descriptor
of the temporary file.
On error, -1 is returned, and
errno
is set appropriately.
ERRORS
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.
CONFORMING TO
4.3BSD, POSIX.1-2001
NOTES
The old behavior (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 does not say anything
about file modes, so the application should make sure its umask
is set appropriately before calling
R mkstemp ().
The prototype is in
<unistd.h>
for libc4, libc5, glibc1; glibc2 follows POSIX.1 and has the prototype in
R <stdlib.h> .
Don't use this function, use
tmpfile(3)
instead. It is better defined and more portable.
SEE ALSO
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