man3/strerror.3

   1 .\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
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  23 .\" References consulted:
  24 .\"     Linux libc source code
  25 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  26 .\"     386BSD man pages
  27 .\" Modified Sat Jul 24 18:05:30 1993 by Rik Faith <faith@cs.unc.edu>
  28 .\" Modified Fri Feb 16 14:25:17 1996 by Andries Brouwer <aeb@cwi.nl>
  29 .\" Modified Sun Jul 21 20:55:44 1996 by Andries Brouwer <aeb@cwi.nl>
  30 .\" Modified Mon Oct 15 21:16:25 2001 by John Levon <moz@compsoc.man.ac.uk>
  31 .\" Modified Tue Oct 16 00:04:43 2001 by Andries Brouwer <aeb@cwi.nl>
  32 .\" Modified Fri Jun 20 03:04:30 2003 by Andries Brouwer <aeb@cwi.nl>
  33 .\"
  34 .TH STRERROR 3  2001-10-16 "" "Linux Programmer's Manual"
  35 .SH NAME
  36 strerror, strerror_r \- return string describing error code
  37 .SH SYNOPSIS
  38 .nf
  39 .B #include <string.h>
  40 .sp
  41 .BI "char *strerror(int " errnum );
  42 .br
  43 .BI "int strerror_r(int " errnum ", char *" buf ", size_t " n );
  44 .fi
  45 .SH DESCRIPTION
  46 The \fBstrerror()\fP function returns a string describing the error
  47 code passed in the argument \fIerrnum\fP, possibly using the LC_MESSAGES
  48 part of the current locale to select the appropriate language.
  49 This string must not be modified by the application, but may be
  50 modified by a subsequent call to \fBperror()\fP or \fBstrerror()\fP.
  51 No library function will modify this string.
  52
  53 The \fBstrerror_r()\fP function is similar to \fBstrerror()\fP, but is
  54 thread safe. It returns the string in the user-supplied buffer
  55 .I buf
  56 of length
  57 .IR n .
  58
  59 .SH "RETURN VALUE"
  60 The \fBstrerror()\fP function returns the appropriate error description
  61 string, or an unknown error message if the error code is unknown.
  62 The value of \fIerrno\fP is not changed for a successful call, and is
  63 set to a nonzero value upon error.
  64 The \fBstrerror_r()\fP function returns 0 on success and \-1 on failure,
  65 setting \fIerrno\fP.
  66
  67 .SH ERRORS
  68 .TP
  69 .B EINVAL
  70 The value of
  71 .I errnum
  72 is not a valid error number.
  73 .TP
  74 .B ERANGE
  75 Insufficient storage was supplied to contain the error description string.
  76
  77 .SH "CONFORMING TO"
  78 SVID 3, POSIX, BSD 4.3, ISO/IEC 9899:1990 (C89).
  79 .br
  80 .BR strerror_r()
  81 with prototype as given above is specified by SUSv3, and was in use
  82 under Digital Unix and HP Unix. An incompatible function, with prototype
  83 .sp
  84 .BI "char *strerror_r(int " errnum ", char *" buf ", size_t " n );
  85 .sp
  86 is a GNU extension used by glibc (since 2.0),
  87 and must be regarded as obsolete in view of SUSv3.
  88 The GNU version may, but need not, use the user-supplied buffer.
  89 If it does, the result may be truncated in case the supplied buffer
  90 is too small. The result is always NUL-terminated.
  91 .SH "SEE ALSO"
  92 .BR errno (3),
  93 .BR perror (3),
  94 .BR strsignal (3)