TEMPNAM(3) Linux Programmer's Manual TEMPNAM(3)
NAME
tempnam - create a name for a temporary file
SYNOPSIS
#include<stdio.h>
char*tempnam(constchar*dir,constchar*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 temp-
nam() 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 argu-
ment 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.
RETURNVALUE
The tempnam() function returns a pointer to a unique temporary file-
name, 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 func-
tion. Use mkstemp(3) instead.
CONFORMINGTO
SVID 2, BSD 4.3
SEEALSO
mktemp(3), mkstemp(3), tmpfile(3), tmpnam(3)
1999-06-14 TEMPNAM(3)
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