char *tempnam(const char *dir, const char *pfx);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
tempnam(): _BSD_SOURCE || _SVID_SOURCE
Never use this function. Use mkstemp(3) or tmpfile(3) instead.
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
a) In case the environment variable TMPDIR exists and contains the name
of an appropriate directory, that is used.
b) Otherwise, if the dir argument is non-NULL and appropriate, it is
c) Otherwise, P_tmpdir (as defined in <stdio.h>) is used when appropri-
d) Finally an implementation-defined directory may be used.
The string returned by tempnam() is allocated using malloc(3) and hence
should be freed by free(3).
On success, the tempnam() function returns a pointer to a unique tempo-
rary filename. It returns NULL if a unique name cannot be generated,
with errno set to indicate the cause of the error.
ENOMEM Allocation of storage failed.
For an explanation of the terms used in this section, see
|Interface | Attribute | Value |
|tempnam() | Thread safety | MT-Safe env |
SVr4, 4.3BSD, POSIX.1-2001. POSIX.1-2008 marks tempnam() as obsolete.
is /tmp (and this is what glibc does).
Because it dynamically allocates memory used to return the pathname,
tempnam() is reentrant, and thus thread safe, unlike tmpnam(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 behavior is implementation defined.
tempnam() uses at most the first five bytes from pfx.
The glibc implementation of tempnam() will fail with the error EEXIST
upon failure to find a unique name.
The precise meaning of "appropriate" is undefined; it is unspecified
how accessibility of a directory is determined.
mkstemp(3), mktemp(3), tmpfile(3), tmpnam(3)
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