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PERROR(3P) POSIX Programmer's Manual PERROR(3P)
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.
perror — write error messages to standard error
#include <stdio.h>
void perror(const char *s);
The functionality described on this reference page is aligned with
the ISO C standard. Any conflict between the requirements described
here and the ISO C standard is unintentional. This volume of
POSIX.1‐2008 defers to the ISO C standard.
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 for update the last data
modification and last file status change timestamps of the file
associated with the standard error stream 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.
On error, perror() shall set the error indicator for the stream to
which stderr points, and shall set errno to indicate the error.
Since no value is returned, an application wishing to check for error
situations should call clearerr(stderr) before calling perror(), then
if ferror(stderr) returns non-zero, the value of errno indicates
which error occurred.
The perror() function shall not return a value.
Refer to fputc(3p).
The following sections are informative.
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 writers may prefer to use alternative interfaces instead
of perror(), such as strerror_r() in combination with fprintf().
None.
None.
fprintf(3p), fputc(3p), psiginfo(3p), strerror(3p)
The Base Definitions volume of POSIX.1‐2008, stdio.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 PERROR(3P)
Pages that refer to this page: stdio.h(0p), psiginfo(3p), setlocale(3p), strerror(3p)