tempnam(3)                                                   tempnam(3)

  tempnam()

  NAME

    tempnam() - temporary file routine

  SYNOPSIS

    #include 

    char * tempnam (const char *dir, char *pfx)

  DESCRIPTION

    The tempnam(3) function is similar to tmpnam(3) in that it returns a
    pointer to a pathname of a file that does not exist at the time of the
    call. Unlike tmpnam(3), you can specify the directory that will contain
    the file (dir) if there is no defined temporary directory, and you can
    specify the filename's prefix, (pfx).

    The tempnam(3) function also looks to use different directories by default
    than does tmpnam(3). It determines the directory for the file using the
    following steps:

   1.     The directory used is the directory defined by TMPDIR if it is
          writeable.
   2.     If the previous step does not produce a usable directory, then the
          directory used is the directory specified by the dir argument if it
          exists and is writeable.
   3.     If the previous step does not produce a usable directory, then the
          directory used is the directory specified by P_tmpdir as declared in
          stdio.h if it exists and is writeable.
   4.     If the previous step does not produce a usable directory, then the
          function attempts to use /tmp.

    The argument pfx, if non-NULL, is used to specify a file name prefix,
    which will be the first part of the created file name. The pfx can be up
    to five characters long.

    Tempnam(3) allocates space for the string; the pointer can be used in a
    call to free(3).

  RETURN VALUES

    The tempnam(3) function returns a pointer to a file name on success, and a
    NULL pointer on error.

  ERRORS

    The tempnam(3) function may fail and set the global variable errno for
    this reason:

    [ENOMEM]
        There isn't enough memory.

  NOTES

    Using tempnam(3) is discouraged for these reasons:
   1.     There can be a race between file name selection and file name
          creation.
   2.     There is no specification for the minimum number of unique temporary
          names; some implementations generate as few as 26 before recycling.
   3.     Some implementations use access(2) to determine whether the temp
          file may be created. this can cause problems for use with setuid(2)
          and setgid(2) programs.

  SEE ALSO

    mktemp(3)

    tmpfile(3)

  USAGE NOTES

    The tempnam function is thread safe.

    The tempnam function is not async-signal safe.