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 the
Xs
with a letter and the current process
ID.
The letter is chosen such that the resulting name
does not duplicate the name of an existing file.
If there are fewer than six
Xs,
the letter is dropped first,
followed by dropping the high-order digits of the process
ID.
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.
APPLICATION USAGE
mktemp()
and
mkstemp()
are thread-safe.
mktemp()
is async-cancel-safe.
mkstemp()
is not async-cancel-safe.
A cancellation point may occur when a thread is executing
mkstemp().
RETURN VALUE
mktemp()
returns its argument except when it runs out of
letters, in which case the result is a pointer
to the 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.
STANDARDS CONFORMANCE
mktemp(): SVID2, SVID3, XPG2
