2.11BSD/src/man/man3/perror.3

.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)perror.3	6.1.1 (2.11BSD) 1996/3/21
.\"
.TH PERROR 3  "March 21, 1996"
.UC 4
.SH NAME
perror, strerror \- system error messages
.SH SYNOPSIS
.nf
.B perror(s)
.B char *s;
.sp
.B #include <string.h>
.sp
.I char *
.B strerror(errnum)
.B int errnum;
.fi
.SH DESCRIPTION
The
.B strerror()
and
.B perror()
functions look up the error message string corresponding to an error number.
.PP
The 
.B strerror()
function accepts an error number argument
.I errnum
and returns a pointer to the corresponding message string.
.PP
The
.B perror()
function
finds the error message corresponding to the current value of the
global variable
.I errno
(intro(2)) and writes it, followed by a newline, to the standard error
file descriptor.  If the argument 
.I string
is non-NULL, it is prepended to the message string and separated
from it by a colon and space (`: ').
If 
.I string
is NULL, only the error message string is printed.
.PP
If
.I errnum
is not a recognized error number, the error message string
will contain ``Unknown error: '' followed by the error number
in decimal.
.PP
The error messages are stored in a data file now rather than an in memory
array.  See 
.BR syserror (5).
.SH "SEE ALSO"
mkerrlst(1),
intro(2),
psignal(3),
strerror(3),
syserror(3),
syserror(5)
.SH BUGS
The
.BR strerror ()
function returns its result in a static buffer which may be
overwritten by subsequent calls.
.PP
The array
.B sys_errlist[]
and the global
.B sys_nerr
are
.B obsolete
and should not be used.  They have, for the time being, been placed in
an object library 
.BR liberrlst.a .