tmpnam(3) Library Functions Manual tmpnam(3)
NAME
tmpnam, tempnam - Construct the name for a temporary file
LIBRARY
Standard C Library (libc.so, libc.a)
SYNOPSIS
#include <stdio.h>
char *tmpnam(
char *s);
char *tempnam(
const char *directory,
const char *prefix);
STANDARDS
Interfaces documented on this reference page conform to industry standards as follows:
tmpnam(), tempnam(): XSH4.2
Refer to the standards(5) reference page for more information about industry standards and associated tags.
PARAMETERS
Specifies the address of an array of at least the number of bytes specified by L_tmpnam, a constant defined in the stdio.h header file.
Points to the pathname of the directory in which the file is to be created. Points to an initial letter sequence with which the filename
begins. The prefix parameter can be null, or it can point to a string of up to 5 bytes to be used as the beginning of the temporary file-
name.
DESCRIPTION
The tmpnam() and tempnam() functions generate filenames for temporary files.
The tmpnam() function generates a filename using the pathname defined as P_tmpdir in the stdio.h header file.
Files created using this function reside in a directory intended for temporary use, and their names are unique. It is the application's
responsibility to use the unlink() function to remove the files when they are no longer needed.
Between the time a filename is created and the file is opened, it is possible for some other process to create a file with the same name.
This should not happen if that other process uses these functions or the mktemp() function, and if the filenames are chosen to make dupli-
cation by other means unlikely.
The tempnam() function allows you to control the choice of a directory. If the directory parameter is null or points to a string that is
not a pathname for an appropriate directory, the pathname defined as P_tmpdir in the stdio.h header file is used. If that pathname is not
accessible, /tmp is used. You can bypass the selection of a pathname by providing an environment variable, TMPDIR, in the user's environ-
ment. The value of the TMPDIR variable is a pathname for the desired temporary file directory.
The prefix parameter can be used to specify a prefix of up to 5 bytes for the temporary filename.
NOTES
If the s parameter is null, the tmpnam() function places its result into an internal thread-specific buffer and returns a pointer to that
area. Subsequent calls to this function from the same thread overwrite this buffer.
The tmpnam() function generates a different filename each time it is called.
[Tru64 UNIX] If tmpnam() is called more than TMP_MAX times by a single process, it starts recycling previously used names.
RETURN VALUES
If the s parameter is null, tmpnam() function places its result into an internal thread-specific buffer and returns a pointer to that area.
If the s parameter is not null, it is assumed to be the address of an array of at least the number of bytes specified by the L_tmpnam con-
stant. The tmpnam() function places its results into that array and returns the value of the s parameter.
Upon successful completion, the tempnam() function returns a pointer to the generated pathname, suitable for use in a subsequent call to
the free() function. Otherwise, null is returned and errno is set to indicate the error.
ERRORS
If the tempnam() function fails, errno may be set to the following value: Insufficient storage space is available.
RELATED INFORMATION
Functions: fopen(3), free(3), malloc(3), mktemp(3), open(2), tmpfile(3), unlink(2)
Standards: standards(5) delim off
tmpnam(3)