Home Man
Today's Posts

Linux & Unix Commands - Search Man Pages

RedHat 9 (Linux i386) - man page for perror (redhat section 3)

PERROR(3)				Library functions				PERROR(3)

       perror - print a system error message

       #include <stdio.h>

       void perror(const char *s);

       #include <errno.h>

       const char *sys_errlist[];
       int sys_nerr;

       The  routine perror() produces a message on the standard error output, describing the last
       error encountered during a call to a system or library function.  First (if s is not  NULL
       and  *s	is  not  NUL)  the argument string s is printed, followed by a colon and a blank.
       Then the message and a new-line.

       To be of most use, the argument string should  include  the  name  of  the  function  that
       incurred  the error.  The error number is taken from the external variable errno, which is
       set when errors occur but not cleared when non-erroneous calls are made.

       The global error list sys_errlist[] indexed by errno can be used to obtain the error  mes-
       sage  without  the  newline.  The largest message number provided in the table is sys_nerr
       -1.  Be careful when directly accessing this list because new error values  may	not  have
       been added to sys_errlist[].

       When  a	system	call  fails, it usually returns -1 and sets the variable errno to a value
       describing what went wrong. (These values can be found in <errno.h>.)  Many library  func-
       tions  do likewise.  The function perror() serves to translate this error code into human-
       readable form.  Note that errno is undefined after a successful library	call:  this  call
       may  well change this variable, even though it succeeds, for example because it internally
       used some other library function that failed.  Thus, if a failing call is not  immediately
       followed by a call to perror, the value of errno should be saved.

       ANSI C, BSD 4.3, POSIX, X/OPEN


					    2001-12-14					PERROR(3)

All times are GMT -4. The time now is 03:33 PM.

Unix & Linux Forums Content Copyrightę1993-2018. All Rights Reserved.
Show Password