PERROR(3C) Standard C Library Functions PERROR(3C)

NAME

perror, errno - print system error messages

SYNOPSIS

#include <stdio.h>

void perror(const char *s)


#include <errno.h>

int errno;

DESCRIPTION

The perror() function produces a message on the standard error output
(file descriptor 2) describing the last error encountered during a
call to a system or library function. The argument string s is
printed, followed by a colon and a blank, followed by the message and
a NEWLINE character. If s is a null pointer or points to a null
string, the colon is not printed. The argument string should include
the name of the program 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. See
Intro(2).


In the case of multithreaded applications, the -mt option must be
specified on the command line at compilation time (see threads(7)).
When the -mt option is specified, errno becomes a macro that enables
each thread to have its own errno. This errno macro can be used on
either side of the assignment as though it were a variable.

USAGE

Messages printed from this function are in the native language
specified by the LC_MESSAGES locale category. See setlocale(3C).

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

SEE ALSO

Intro(2), fmtmsg(3C), gettext(3C), setlocale(3C), strerror(3C),
attributes(7), standards(7), threads(7)

July 12, 2007 PERROR(3C)