perror (3p) - Linux Manuals

perror: write error messages to standard error

PROLOG

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

perror - write error messages to standard error

SYNOPSIS

#include <stdio.h>

void perror(const char *s);

DESCRIPTION

The perror() function shall map the error number accessed through the symbol errno to a language-dependent error message, which shall be written to the standard error stream as follows:

*

First (if s is not a null pointer and the character pointed to by s is not the null byte), the string pointed to by s followed by a colon and a <space>.

*

Then an error message string followed by a <newline>.

The contents of the error message strings shall be the same as those returned by strerror() with argument errno.

The perror() function shall mark the file associated with the standard error stream as having been written (st_ctime, st_mtime marked for update) at some time between its successful completion and exit(), abort(), or the completion of fflush() or fclose() on stderr.

The perror() function shall not change the orientation of the standard error stream.

RETURN VALUE

The perror() function shall not return a value.

ERRORS

No errors are defined.

The following sections are informative.

EXAMPLES

Printing an Error Message for a Function

The following example replaces bufptr with a buffer that is the necessary size. If an error occurs, the perror() function prints a message and the program exits.

#include <stdio.h>
#include <stdlib.h>
...
char *bufptr;
size_t szbuf;
...
if ((bufptr = malloc(szbuf)) == NULL) {
    perror("malloc"); exit(2);
}
...

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .