mktemp.3c (2010 09)

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mktemp(3C) mktemp(3C)
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 tem-
plate 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().
SEE ALSO
getpid(2), open(2), tmpfile(3S), tmpnam(3S), thread_safety(5).
STANDARDS CONFORMANCE
mktemp(): SVID2, SVID3, XPG2
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1