tmpfile(3) Library Functions Manual tmpfile(3)

tmpfile - create a temporary file

Standard C library (libc, -lc)

#include <stdio.h>
FILE *tmpfile(void);

The tmpfile() function opens a unique temporary file in binary read/write (w+b) mode. The file will be automatically deleted when it is closed or the program terminates.

The tmpfile() function returns a stream descriptor, or NULL if a unique filename cannot be generated or the unique file cannot be opened. In the latter case, errno is set to indicate the error.

Search permission denied for directory in file's path prefix.
Unable to generate a unique filename.
The call was interrupted by a signal; see signal(7).
The per-process limit on the number of open file descriptors has been reached.
The system-wide limit on the total number of open files has been reached.
There was no room in the directory to add the new filename.
Read-only filesystem.

For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
tmpfile () Thread safety MT-Safe

The standard does not specify the directory that tmpfile() will use. glibc will try the path prefix P_tmpdir defined in <stdio.h>, and if that fails, then the directory /tmp.

C11, POSIX.1-2008.

POSIX.1-2001, C89, SVr4, 4.3BSD, SUSv2.

POSIX.1-2001 specifies: an error message may be written to stdout if the stream cannot be opened.

exit(3), mkstemp(3), mktemp(3), tempnam(3), tmpnam(3)

2024-05-02 Linux man-pages 6.8