tmpfile - create a temporary file
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
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.
For an explanation of the terms used in this section, see attributes(7).
- 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
- The system-wide limit on the total number of open files has been
- There was no room in the directory to add the new filename.
- Read-only filesystem.
POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD, SUSv2.
POSIX.1-2001 specifies: an error message may be written to stdout if the
stream cannot be opened.
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
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