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| -rw-r--r-- | man3/perror.3 | 143 |
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diff --git a/man3/perror.3 b/man3/perror.3 new file mode 100644 index 0000000..efb3e6f --- /dev/null +++ b/man3/perror.3 @@ -0,0 +1,143 @@ +'\" t +.\" Copyright (c) 1994 Michael Haardt (michael@moria.de), 1994-06-04 +.\" Copyright (c) 1995 Michael Haardt +.\" (michael@cantor.informatik.rwth-aachen.de), 1995-03-16 +.\" Copyright (c) 1996 Andries Brouwer (aeb@cwi.nl), 1996-01-13 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" 1996-01-13 aeb: merged in some text contributed by Melvin Smith +.\" (msmith@falcon.mercer.peachnet.edu) and various other changes. +.\" Modified 1996-05-16 by Martin Schulze (joey@infodrom.north.de) +.\" +.TH perror 3 2023-07-20 "Linux man-pages 6.05.01" +.SH NAME +perror \- print a system error message +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.B #include <stdio.h> +.PP +.BI "void perror(const char *" s ); +.PP +.B #include <errno.h> +.PP +.BI "int " errno "; \fR/* Not really declared this way; see errno(3) */" +.PP +.BI "[[deprecated]] const char *const " sys_errlist []; +.BI "[[deprecated]] int " sys_nerr ; +.fi +.PP +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.PP +.IR sys_errlist , +.IR sys_nerr : +.nf + From glibc 2.19 to glibc 2.31: + _DEFAULT_SOURCE + glibc 2.19 and earlier: + _BSD_SOURCE +.fi +.SH DESCRIPTION +The +.BR perror () +function produces a message on standard error describing the last +error encountered during a call to a system or library function. +.PP +First (if +.I s +is not NULL and +.I *s +is not a null byte (\[aq]\e0\[aq])), the argument string +.I s +is printed, followed by a colon and a blank. +Then an error message corresponding to the current value of +.I errno +and a new-line. +.PP +To be of most use, the argument string should include the name +of the function that incurred the error. +.PP +The global error list +.IR sys_errlist "[]," +which can be indexed by +.IR errno , +can be used to obtain the error message without the newline. +The largest message number provided in the table is +.IR sys_nerr "\-1." +Be careful when directly accessing this list, because new error values +may not have been added to +.IR sys_errlist "[]." +The use of +.IR sys_errlist "[]" +is nowadays deprecated; use +.BR strerror (3) +instead. +.PP +When a system call fails, it usually returns \-1 and sets the +variable +.I errno +to a value describing what went wrong. +(These values can be found in +.IR <errno.h> .) +Many library functions do likewise. +The function +.BR perror () +serves to translate this error code into human-readable form. +Note that +.I errno +is undefined after a successful system call or library function 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 +.BR perror (), +the value of +.I errno +should be saved. +.SH ATTRIBUTES +For an explanation of the terms used in this section, see +.BR attributes (7). +.TS +allbox; +lbx lb lb +l l l. +Interface Attribute Value +T{ +.na +.nh +.BR perror () +T} Thread safety MT-Safe race:stderr +.TE +.sp 1 +.SH STANDARDS +.TP +.I errno +.TQ +.BR perror () +C11, POSIX.1-2008. +.TP +.I sys_nerr +.TQ +.I sys_errlist +BSD. +.SH HISTORY +.TP +.I errno +.TQ +.BR perror () +POSIX.1-2001, C89, 4.3BSD. +.TP +.I sys_nerr +.TQ +.I sys_errlist +Removed in glibc 2.32. +.SH SEE ALSO +.BR err (3), +.BR errno (3), +.BR error (3), +.BR strerror (3) |