ERROR(3)                            Linux Programmer's Manual                            ERROR(3)



NAME
       error,  error_at_line,  error_message_count,  error_one_per_line,  error_print_progname  -
       glibc error reporting functions

SYNOPSIS
       #include <error.h>

       void error(int status, int errnum, const char *format, ...);

       void error_at_line(int status, int errnum, const char *filename,
                          unsigned int linenum, const char *format, ...);

       extern unsigned int error_message_count;

       extern int error_one_per_line;

       extern void (*error_print_progname) (void);

DESCRIPTION
       error() is a general error-reporting function.  It flushes stdout,  and  then  outputs  to
       stderr the program name, a colon and a space, the message specified by the printf(3)-style
       format string format, and, if errnum is nonzero, a second colon and a  space  followed  by
       the  string  given  by  strerror(errnum).  Any arguments required for format should follow
       format in the argument list.  The output is terminated by a newline character.

       The program name printed by error() is the value of the  global  variable  program_invoca‐
       tion_name(3).   program_invocation_name  initially has the same value as main()'s argv[0].
       The value of this variable can be modified to change the output of error().

       If status has a nonzero value, then error() calls exit(3) to terminate the  program  using
       the given value as the exit status.

       The  error_at_line()  function  is exactly the same as error(), except for the addition of
       the arguments filename and linenum.  The output produced is as for  error(),  except  that
       after the program name are written: a colon, the value of filename, a colon, and the value
       of linenum.  The preprocessor values __LINE__ and __FILE__  may  be  useful  when  calling
       error_at_line(),  but  other  values can also be used.  For example, these arguments could
       refer to a location in an input file.

       If the global variable error_one_per_line is set nonzero, a  sequence  of  error_at_line()
       calls  with  the  same  value of filename and linenum will result in only one message (the
       first) being output.

       The global variable error_message_count counts the number of messages that have been  out‐
       put by error() and error_at_line().

       If  the  global variable error_print_progname is assigned the address of a function (i.e.,
       is not NULL), then that function is called instead of prefixing the message with the  pro‐
       gram name and colon.  The function should print a suitable string to stderr.

CONFORMING TO
       These  functions  and  variables  are  GNU  extensions, and should not be used in programs
       intended to be portable.

SEE ALSO
       err(3), errno(3), exit(3), perror(3), program_invocation_name(3), strerror(3)

COLOPHON
       This page is part of release 3.74 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at http://www.kernel.org/doc/man-pages/.



GNU                                         2010-08-29                                   ERROR(3)