Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
PERROR(3)		   Linux Programmer's Manual		     PERROR(3)

NAME
       perror -	print a	system error message

SYNOPSIS
       #include	<stdio.h>

       void perror(const char *s);

       #include	<errno.h>

       const char *sys_errlist[];
       int sys_nerr;
       int errno;

   Feature Test	Macro Requirements for glibc (see feature_test_macros(7)):

       sys_errlist, sys_nerr: _BSD_SOURCE

DESCRIPTION
       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 a null byte
       ('\0')) 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 successful calls are made.

       The global error	list sys_errlist[] indexed by errno  can  be  used  to
       obtain the error	message	without	the newline.  The largest message num-
       ber 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 functions 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 per-
       ror(), the value	of errno should	be saved.

CONFORMING TO
       The function perror() and the external errno (see errno(3)) conform  to
       C89, C99, 4.3BSD, POSIX.1-2001.	The externals sys_nerr and sys_errlist
       conform to BSD.

NOTES
       The externals sys_nerr and sys_errlist are defined  by  glibc,  but  in
       _stdio.h_.

SEE ALSO
       err(3), errno(3), error(3), strerror(3)

COLOPHON
       This  page  is  part of release 3.25 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found	at http://www.kernel.org/doc/man-pages/.

				  2007-07-26			     PERROR(3)

NAME | SYNOPSIS | DESCRIPTION | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=perror&sektion=3&manpath=SuSE+Linux%2fi386+11.3>

home | help