PERROR(3P)                                          POSIX Programmer's Manual                                         PERROR(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       perror - write error messages to standard error

SYNOPSIS
       #include <stdio.h>

       void perror(const char *s);


DESCRIPTION
       The perror() function shall map the error number accessed through the symbol errno to a language-dependent error message,
       which shall be written to the standard error stream as follows:

        * First (if s is not a null pointer and the character pointed to by s is not the null byte), the string pointed to by  s
          followed by a colon and a <space>.

        * Then an error message string followed by a <newline>.

       The contents of the error message strings shall be the same as those returned by strerror() with argument errno.

       The  perror()  function  shall  mark the file associated with the standard error stream as having been written (st_ctime,
       st_mtime marked for update) at some time between its successful completion and exit(),  abort(),  or  the  completion  of
       fflush() or fclose() on stderr.

       The perror() function shall not change the orientation of the standard error stream.

RETURN VALUE
       The perror() function shall not return a value.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
   Printing an Error Message for a Function
       The following example replaces bufptr with a buffer that is the necessary size. If an error occurs, the perror() function
       prints a message and the program exits.


              #include <stdio.h>
              #include <stdlib.h>
              ...
              char *bufptr;
              size_t szbuf;
              ...
              if ((bufptr = malloc(szbuf)) == NULL) {
                  perror("malloc"); exit(2);
              }
              ...

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       strerror(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdio.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy  between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group
       Standard  is  the  referee   document.   The   original   Standard   can   be   obtained   online   at   http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                    PERROR(3P)