FreeBSD 7.0 manual page repository

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err, verr, errc, verrc, errx, verrx, warn, vwarn, warnc, vwarnc, warnx,

 

NAME

      err, verr, errc, verrc, errx, verrx, warn, vwarn, warnc, vwarnc, warnx,
      vwarnx, err_set_exit, err_set_file - formatted error messages
 

LIBRARY

      Standard C Library (libc, -lc)
 

SYNOPSIS

      #include <err.h>
 
      void
      err(int eval, const char *fmt, ...);
 
      void
      err_set_exit(void (*exitf)(int));
 
      void
      err_set_file(void *vfp);
 
      void
      errc(int eval, int code, const char *fmt, ...);
 
      void
      errx(int eval, const char *fmt, ...);
 
      void
      warn(const char *fmt, ...);
 
      void
      warnc(int code, const char *fmt, ...);
 
      void
      warnx(const char *fmt, ...);
 
      #include <stdarg.h>
 
      void
      verr(int eval, const char *fmt, va_list args);
 
      void
      verrc(int eval, int code, 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
      vwarnc(int code, 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, or on another file specified using the
      err_set_file() function.  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 out‐
      put is terminated by a newline character.
 
      The err(), errc(), verr(), verrc(), warn(), warnc(), vwarn(), and
      vwarnc() functions append an error message obtained from strerror(3)
      based on a supplied error code value or the global variable errno, pre‐
      ceded by another colon and space unless the fmt argument is NULL.
 
      In the case of the errc(), verrc(), warnc(), and vwarnc() functions, the
      code argument is used to look up the error message.
 
      The err(), verr(), warn(), and vwarn() functions use the global variable
      errno to look up the error message.
 
      The errx() and warnx() functions do not append an error message.
 
      The err(), verr(), errc(), verrc(), errx(), and verrx() functions do not
      return, but exit with the value of the argument eval.  It is recommended
      that the standard values defined in sysexits(3) be used for the value of
      eval.  The err_set_exit() function can be used to specify a function
      which is called before exit(3) to perform any necessary cleanup; passing
      a null function pointer for exitf resets the hook to do nothing.  The
      err_set_file() function sets the output stream used by the other func‐
      tions.  Its vfp argument must be either a pointer to an open stream (pos‐
      sibly already converted to void *) or a null pointer (in which case the
      output stream is set to standard error).
 

EXAMPLES

      Display the current errno information string and exit:
 
            if ((p = malloc(size)) == NULL)
                    err(1, NULL);
            if ((fd = open(file_name, O_RDONLY, 0)) == -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:
 
            if ((fd = open(raw_device, O_RDONLY, 0)) == -1)
                    warnx("%s: %s: trying the block device",
                        raw_device, strerror(errno));
            if ((fd = open(block_device, O_RDONLY, 0)) == -1)
                    err(1, "%s", block_device);
 
      Warn of an error without using the global variable errno:
 
            error = my_function();  /* returns a value from <errno.h> */
            if (error != 0)
                    warnc(error, "my_function");
      exit(3), fmtmsg(3), printf(3), strerror(3), sysexits(3)
 

HISTORY

      The err() and warn() functions first appeared in 4.4BSD.  The
      err_set_exit() and err_set_file() functions first appeared in
      FreeBSD 2.1.  The errc() and warnc() functions first appeared in
      FreeBSD 3.0.
 

Sections

Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.