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
   message 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
   message  obtained  from strerror(3) based on the global variable errno,
   preceded 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

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   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/.

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