NAME¶
tempnam - create a name for a temporary file
SYNOPSIS¶
#include <stdio.h>
char *tempnam(const char *dir, const char *pfx);
DESCRIPTION¶
The
tempnam() function returns a pointer to a string that is a valid
filename, and such that a file with this name did not exist when
tempnam() checked. The filename suffix of the pathname generated will
start with
pfx in case
pfx is a non-NULL string of at most five
bytes. The directory prefix part of the pathname generated is required to be
`appropriate' (often that at least implies writable). Attempts to find an
appropriate directory go through the following steps: (i) In case the
environment variable TMPDIR exists and contains the name of an appropriate
directory, that is used. (ii) Otherwise, if the
dir argument is
non-NULL and appropriate, it is used. (iii) Otherwise, P_tmpdir (as defined in
<stdio.h>) is used when appropriate. (iv) Finally an
implementation-defined directory may be used.
RETURN VALUE¶
The
tempnam() function returns a pointer to a unique temporary filename,
or NULL if a unique name cannot be generated.
ERRORS¶
- ENOMEM
- Allocation of storage failed.
NOTES¶
SUSv2 does not mention the use of TMPDIR; glibc will use it only when the
program is not suid. SVID2 specifies that the directory used under (iv) is
/tmp. SVID2 specifies that the string returned by
tempnam() was
allocated using
malloc(3) and hence can be freed by
free(3).
The
tempnam() function generates a different string each time it is
called, up to TMP_MAX (defined in
<stdio.h>) times. If it is
called more than TMP_MAX times, the behaviour is implementation defined.
In case the
pfx argument has length larger than five, glibc will use the
first five bytes. Upon failure to find a unique name, glibc will return
EEXIST.
BUGS¶
The precise meaning of `appropriate' is undefined; it is unspecified how
accessibility of a directory is determined. Never use this function. Use
mkstemp(3) instead.
SVID 2, BSD 4.3
SEE ALSO¶
mktemp(3),
mkstemp(3),
tmpfile(3),
tmpnam(3)
