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strerror(3) [ultrix man page]

perror(3)						     Library Functions Manual							 perror(3)

Name
       perror, strerror, sys_errlist, sys_nerr - system error messages

Syntax
       void perror(s)
       char *s;

       int sys_nerr;
       char *sys_errlist[];

       #include <string.h>

       char *strerror(err)
       int err;

Description
       The  subroutine produces a short error message on the standard error file describing the last error encountered during a call to the system
       from a C program.  First the argument string s , if it is not a null pointer, is printed followed by a colon and a space; then the  message
       and  a  new line are printed.  Most usefully, the argument string is the name of the program which incurred the error.  The error number is
       taken from the external variable errno which is set when errors occur but not cleared when nonerroneous calls are made.	For further infor-
       mation, see

       To  simplify  variant  formatting of messages, the vector of message strings sys_errlist is provided; errno can be used as an index in this
       table to get the message string without the new line.  The sys_nerr is the number of messages provided for  in  the  table;  it	should	be
       checked	because new error codes may be added to the system before they are added to the table.	The function will also return a pointer to
       the message text for a given error number.

See Also
       intro(2), psignal(3)

																	 perror(3)

Check Out this Related Man Page

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 ('')) 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[]. The use of sys_errlist[] is nowadays deprecated. 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 perror(), 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 3.53 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/. 2012-04-17 PERROR(3)
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