NAME
mktemp(), mkstemp() — make a unique file name
SYNOPSIS
#include <stdlib.h>
char *mktemp(char *template);
int mkstemp(char *template);
Remarks
These functions are provided solely
for backward compatibility and importability of applications,
and are not recommended for new applications
where portability is important.
For portable applications, use
tmpfile()
instead (see
tmpfile(3S)).
DESCRIPTION
mktemp()
replaces the contents of the string pointed to by
template
by a unique file name, and returns the address of
template.
The string in
template
should look like a file name with six trailing
Xs;
mktemp()
replaces each
X
with a single byte character from the portable filename
character set. The letter is chosen such that the resulting
name does not duplicate the name of an existing file.
mkstemp()
makes the same replacement to the template,
but also returns a file descriptor for the template file
after opening the file for reading and writing.
mkstemp()
thus prevents any possible race condition
between testing whether the file exists and opening it for use.
RETURN VALUE
mktemp()
returns its argument except when it runs out of
letters or an underlying service fails, in which case the result
is a pointer to an empty string
"".
mkstemp()
returns an open file descriptor upon successful completion,
or -1 if no suitable file could be created.
WARNINGS
It is possible to run out of letters.
mktemp()
and
mkstemp()
do not check to determine whether the file name part of
template
exceeds the maximum allowable file name length.
Setting
process_id_max
kernel tunable to values greater than 99999 can have an effect
on formation of temporary filenames in
mktemp()
and
mkstemp().
Formation of temporary filenames using process ids may not be
supported in future versions of
mktemp()
and
mkstemp().
STANDARDS CONFORMANCE
mktemp(): SVID2, SVID3, XPG2
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