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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 stan- dards as follows: tmpnam(), tempnam(): XPG4, XPG4-UNIX Refer to the standards(5) reference page for more information about in- dustry standards and associated tags. PARAMETERS Specifies the address of an array of at least the number of bytes spec- ified 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 cre- ated. Points to an initial letter sequence with which the filename be- gins. 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 filename. 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 re- sponsibility 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 duplica- tion 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 environment. The value of the TMPDIR variable is a pathname for the desired temporary file di- rectory. 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. [Digital] 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 indi- cate 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), tmp- file(3), unlink(2) Standards: standards(5) delim off tmpnam(3)