1 .\" Copyright (C) 2006 Justin Pryzby <pryzbyj@justinpryzby.com>
2 .\" and Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
4 .\" %%%LICENSE_START(PERMISSIVE_MISC)
5 .\" Permission is hereby granted, free of charge, to any person obtaining
6 .\" a copy of this software and associated documentation files (the
7 .\" "Software"), to deal in the Software without restriction, including
8 .\" without limitation the rights to use, copy, modify, merge, publish,
9 .\" distribute, sublicense, and/or sell copies of the Software, and to
10 .\" permit persons to whom the Software is furnished to do so, subject to
11 .\" the following conditions:
13 .\" The above copyright notice and this permission notice shall be
14 .\" included in all copies or substantial portions of the Software.
16 .\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 .\" EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 .\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
19 .\" IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
20 .\" CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
21 .\" TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
22 .\" SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
26 .\" glibc manual and source
27 .TH ERROR 3 2021-03-22 "GNU" "Linux Programmer's Manual"
29 error, error_at_line, error_message_count, error_one_per_line,
30 error_print_progname \- glibc error reporting functions
35 .BI "void error(int " status ", int " errnum ", const char *" format ", ...);"
36 .BI "void error_at_line(int " status ", int " errnum ", const char *" filename ,
37 .BI " unsigned int " linenum ", const char *" format ", ...);"
39 .BI "extern unsigned int " error_message_count ;
40 .BI "extern int " error_one_per_line ;
42 .BI "extern void (*" error_print_progname ")(void);"
46 is a general error-reporting function.
51 the program name, a colon and a space, the message specified by the
53 format string \fIformat\fP, and, if \fIerrnum\fP is
54 nonzero, a second colon and a space followed by the string given by
55 .IR strerror(errnum) .
56 Any arguments required for
61 The output is terminated by a newline character.
63 The program name printed by
65 is the value of the global variable
66 .BR program_invocation_name (3).
67 .I program_invocation_name
68 initially has the same value as
71 The value of this variable can be modified to change the output of
74 If \fIstatus\fP has a nonzero value, then
78 to terminate the program using the given value as the exit status;
79 otherwise it returns after printing the error message.
83 function is exactly the same as
85 except for the addition of the arguments
89 The output produced is as for
91 except that after the program name are written: a colon, the value of
93 a colon, and the value of
95 The preprocessor values \fB__LINE__\fP and
96 \fB__FILE__\fP may be useful when calling
98 but other values can also be used.
99 For example, these arguments could refer to a location in an input file.
101 If the global variable \fIerror_one_per_line\fP is set nonzero,
105 same value of \fIfilename\fP and \fIlinenum\fP will result in only
106 one message (the first) being output.
108 The global variable \fIerror_message_count\fP counts the number of
109 messages that have been output by
112 .BR error_at_line ().
114 If the global variable \fIerror_print_progname\fP
115 is assigned the address of a function
116 (i.e., is not NULL), then that function is called
117 instead of prefixing the message with the program name and colon.
118 The function should print a suitable string to
121 For an explanation of the terms used in this section, see
129 Interface Attribute Value
132 T} Thread safety MT-Safe locale
136 MT-Unsafe\ race: error_at_line/\:error_one_per_line locale
144 .I error_one_per_line
145 variable is accessed (without any form of synchronization, but since it's an
147 used once, it should be safe enough) and, if
148 .I error_one_per_line
149 is set nonzero, the internal static variables (not exposed to users)
150 used to hold the last printed filename and line number are accessed
151 and modified without synchronization; the update is not atomic and it
152 occurs before disabling cancellation, so it can be interrupted only after
153 one of the two variables is modified.
159 These functions and variables are GNU extensions, and should not be
160 used in programs intended to be portable.
166 .BR program_invocation_name (3),