TMPNAM(3S-SVR3)     RISC/os Reference Manual      TMPNAM(3S-SVR3)



NAME
     tmpnam, tempnam - create a name for a temporary file

SYNOPSIS
     #include <stdio.h>

     char *tmpnam (s)
     char *s;

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

DESCRIPTION
     These functions generate file names that can safely be used
     for a temporary file.

     tmpnam always generates a file name using the path-prefix
     defined as P_tmpdir in the <stdio.h> header file.  If s is
     NULL, tmpnam leaves its result in an internal static area
     and returns a pointer to that area.  The next call to tmpnam
     will destroy the contents of the area.  If s is not NULL, it
     is assumed to be the address of an array of at least
     L_tmpnam bytes, where L_tmpnam is a constant defined in
     <stdio.h>; tmpnam places its result in that array and
     returns s.

     tempnam allows the user to control the choice of a direc-
     tory.  The argument dir points to the name of the directory
     in which the file is to be created.  If dir is NULL or
     points to a string that is not a name for an appropriate
     directory, the path-prefix defined as P_tmpdir in the
     <stdio.h> header file is used.  If that directory is not
     accessible, /tmp will be used as a last resort.  This entire
     sequence can be up-staged by providing an environment vari-
     able TMPDIR in the user's environment, whose value is the
     name of the desired temporary-file directory.

     Many applications prefer their temporary files to have cer-
     tain favorite initial letter sequences in their names.  Use
     the pfx argument for this.  This argument may be NULL or
     point to a string of up to five characters to be used as the
     first few characters of the temporary-file name.

     tempnam uses malloc(3C) to get space for the constructed
     file name, and returns a pointer to this area.  Thus, any
     pointer value returned from tempnam may serve as an argument
     to free [see malloc(3C)].  If tempnam cannot return the
     expected result for any reason, i.e.  malloc(3C) failed, or
     none of the above mentioned attempts to find an appropriate
     directory was successful, a NULL pointer will be returned.





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TMPNAM(3S-SVR3)     RISC/os Reference Manual      TMPNAM(3S-SVR3)



NOTES
     These functions generate a different file name each time
     they are called.

     Files created using these functions and either fopen(3S) or
     creat(2) are temporary only in the sense that they reside in
     a directory intended for temporary use, and their names are
     unique.  It is the user's responsibility to use unlink(2) to
     remove the file when its use is ended.

SEE ALSO
     creat(2), unlink(2), fopen(3S), malloc(3C), mktemp(3C),
     tmpfile(3S).

CAVEATS
     If called more than 17,576 times in a single process, these
     functions will start recycling previously used names.

     Between the time a file name is created and the file is
     opened, it is possible for some other process to create a
     file with the same name.  This can never happen if that
     other process is using these functions or mktemp, and the
     file names are chosen to render duplication by other means
     unlikely.































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