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ERR(3)                     Linux Programmer's Manual                    ERR(3)
NAME
       err,  verr,  errx,  verrx, warn, vwarn, warnx, vwarnx - formatted error
       messages
SYNOPSIS
       #include <err.h>
       void err(int eval, const char *fmt, ...);
       void errx(int eval, const char *fmt, ...);
       void warn(const char *fmt, ...);
       void warnx(const char *fmt, ...);
       #include <stdarg.h>
       void verr(int eval, const char *fmt, va_list args);
       void verrx(int eval, const char *fmt, va_list args);
       void vwarn(const char *fmt, va_list args);
       void vwarnx(const char *fmt, va_list args);
DESCRIPTION
       The err() and warn() family of functions display a formatted error mes-
       sage on the standard error output.  In all cases, the last component of
       the program name, a colon character, and a space are  output.   If  the
       fmt argument is not NULL, the printf(3)-like formatted error message is
       output.  The output is terminated by a newline character.
       The err(), verr(), warn(), and vwarn() functions append an  error  mes-
       sage obtained from strerror(3) based on the global variable errno, pre-
       ceded by another colon and space unless the fmt argument is NULL.
       The errx() and warnx() functions do not append an error message.
       The err(), verr(), errx(), and verrx() functions  do  not  return,  but
       exit with the value of the argument eval.
ATTRIBUTES
       For   an   explanation   of   the  terms  used  in  this  section,  see
       attributes(7).
       +------------------+---------------+----------------+
       |Interface         | Attribute     | Value          |
       +------------------+---------------+----------------+
       |err(), errx(),    | Thread safety | MT-Safe locale |
       |warn(), warnx(),  |               |                |
       |verr(), verrx(),  |               |                |
       |vwarn(), vwarnx() |               |                |
       +------------------+---------------+----------------+
CONFORMING TO
       These functions are nonstandard BSD extensions.
EXAMPLE
       Display the current errno information string and exit:
           p = malloc(size);
           if (p == NULL)
               err(1, NULL);
           fd = open(file_name, O_RDONLY, 0);
           if (fd == -1)
               err(1, "%s", file_name);
       Display an error message and exit:
           if (tm.tm_hour < START_TIME)
               errx(1, "too early, wait until %s", start_time_string);
       Warn of an error:
           fd = open(raw_device, O_RDONLY, 0);
           if (fd == -1)
               warnx("%s: %s: trying the block device",
                       raw_device, strerror(errno));
           fd = open(block_device, O_RDONLY, 0);
           if (fd == -1)
               err(1, "%s", block_device);
SEE ALSO
       error(3), exit(3), perror(3), printf(3), strerror(3)
COLOPHON
       This page is part of release 4.15 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
       https://www.kernel.org/doc/man-pages/.
Linux                             2017-09-15                            ERR(3)