error, error_at_line, error_message_count, error_one_per_line,
error_print_progname - glibc error reporting functions
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);
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
The program name printed by error() is the value of the global variable
program_invocation_name(3). program_invocation_name initially has the
same value as main()'s argv. 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 output 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 program name and colon. The function
should print a suitable string to stderr.
These functions and variables are GNU extensions, and should not be
used in programs intended to be portable.
err(3), errno(3), exit(3), perror(3), program_invocation_name(3),
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be found at http://www.kernel.org/doc/man-pages/.