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


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


     #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);


     error() is a general error-reporting function.  It flushes stdout,  and
     then  outputs to stderr the program name, a colon and a space, the mes-
     sage 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 new-
     line character.
     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[0].  The value of this variable can be mod-
     ified 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 pro-
     duced is as for error(), except that after the program name  are  writ-
     ten: a colon, the value of filename, a colon, and the value of linenum.
     The preprocessor values __LINE__ and __FILE__ may be useful when  call-
     ing  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.


     For  an  explanation  of  the  terms  used   in   this   section,   see
     allbox; lb lb lbw33 l l l.  Interface Attribute Value T{ error()
     T}   Thread safety   MT-Safe locale T{ error_at_line() T}   Thread
     safety  T{ MT-Unsafe race: error_at_line/error_one_per_line locale T}
     The  internal error_one_per_line variable is accessed (without any form
     of synchronization, but since it's an int used once, it should be  safe
     enough)  and, if error_one_per_line is set nonzero, the internal static
     variables (not exposed to users) used to hold the last printed filename
     and  line number are accessed and modified without synchronization; the
     update is not atomic and it occurs before disabling cancellation, so it
     can  be  interrupted  only  after one of the two variables is modified.
     After that, error_at_line() is very much like error().


     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), str-


     This page is part of release 4.16 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

GNU 2017-09-15 ERROR(3)

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