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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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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.1‐2017 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.1‐2017, stdio.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 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 .
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 2017 PERROR(3P)
Pages that refer to this page: stdio.h(0p), close(3p), psiginfo(3p), setlocale(3p), strerror(3p)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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