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, Copyright (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.opengroup.org/unix/online.html .