Section: Linux Programmer's Manual (3)
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tmpnam, tmpnam_r - create a name for a temporary file
char *tmpnam(char *s);
char *tmpnam_r(char *s);
Feature Test Macro Requirements for glibc (see
- Since glibc 2.19:
- Up to and including glibc 2.19:
_BSD_SOURCE || _SVID_SOURCE
avoid using these functions; use
function returns a pointer to a string that is a valid filename,
and such that a file with this name did not exist at some point
in time, so that naive programmers may think it
a suitable name for a temporary file.
If the argument
is NULL, this name is generated in an internal static buffer
and may be overwritten by the next call to
is not NULL, the name is copied to the character array (of length
pointed to by
and the value
is returned in case of success.
The created pathname has a directory prefix
are defined in
just like the
function performs the same task as
but returns NULL (to indicate an error) if
These functions return a pointer to a unique temporary
filename, or NULL if a unique name cannot be generated.
No errors are defined.
For an explanation of the terms used in this section, see
||Thread safety||MT-Unsafe race:tmpnam/!s|
SVr4, 4.3BSD, C89, C99, POSIX.1-2001.
is a nonstandard extension that is also available
on a few other systems.
function generates a different string each time it is called,
If it is called more than
the behavior is implementation defined.
Although these functions generate names that are difficult to guess,
it is nevertheless possible that between the time that
the pathname is returned and the time that the program opens it,
another program might create that pathname using
or create it as a symbolic link.
This can lead to security holes.
To avoid such possibilities, use the
flag to open the pathname.
Or better yet, use
Portable applications that use threads cannot call
with a NULL argument if either
Never use these functions.
This page is part of release 4.16 of the Linux
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