sysexits.h - exit codes for programs

       The choice of an appropriate exit value is often ambiguous.

       A few programs exit with the following error codes.

       The  successful  exit  is  always  indicated  by a status of 0, or EX_OK (equivalent to EXIT_SUCCESS from
       <stdlib.h>).  Error numbers begin at EX__BASE to reduce the  possibility  of  clashing  with  other  exit
       statuses that random programs may already return.  The meaning of the code is approximately as follows:

       EX_USAGE
              The command was used incorrectly, e.g., with the wrong number of arguments, a bad flag, bad syntax
              in a parameter, or whatever.

       EX_DATAERR
              The input data was incorrect in some way.  This should only be used for user's data and not system
              files.

       EX_NOINPUT
              An  input  file  (not  a  system file) did not exist or was not readable.  This could also include
              errors like "No message" to a mailer (if it cared to catch it).

       EX_NOUSER
              The user specified did not exist.  This might be used for mail addresses or remote logins.

       EX_NOHOST
              The host specified did not exist.  This is used in mail addresses or network requests.

       EX_UNAVAILABLE
              A service is unavailable.  This can occur if a support program or file does not exist.   This  can
              also  be  used  as a catch-all message when something you wanted to do doesn't work, but you don't
              know why.

       EX_SOFTWARE
              An internal software error has been detected.  This should  be  limited  to  non-operating  system
              related errors if possible.

       EX_OSERR
              An  operating  system  error  has  been  detected.  This is intended to be used for such things as
              "cannot fork", "cannot create pipe", or the like.  It includes things like getuid(2)  returning  a
              user that does not exist in the passwd(5) file.

       EX_OSFILE
              Some  system  file  (e.g., /etc/passwd, /etc/utmp, etc.)  does not exist, cannot be opened, or has
              some sort of error (e.g., syntax error).

       EX_CANTCREAT
              A (user specified) output file cannot be created.

       EX_IOERR
              An error occurred while doing I/O on some file.

       EX_TEMPFAIL
              Temporary failure, indicating something that is not really an error.  For example  that  a  mailer
              could not create a connection, and the request should be reattempted later.

       EX_PROTOCOL
              The remote system returned something that was "not possible" during a protocol exchange.

       EX_OSFILE
              You  did  not  have sufficient permission to perform the operation.  This is not intended for file
              system problems, which should  use  EX_NOINPUT  or  EX_CANTCREAT,  but  rather  for  higher  level
              permissions.

       EX_CONFIG
              Something was found in an unconfigured or misconfigured state.

       The numerical values corresponding to the symbolical ones are given in parenthesis for easy reference.

       The  <sysexits.h>  file  appeared  in  4.0BSD  for  use  by  the  deliverymail  utility, later renamed to
       sendmail(8).

       Standard C library (libc)

       sysexits.h - exit codes for programs

err(3), error(3), exit(3)

Linux man-pages 6.9.1                              2024-05-02                                  sysexits.h(3head)

       BSD.

#include<sysexits.h>#defineEX_OK0    /* successful termination */

       #defineEX__BASE64   /* base value for error messages */

       #defineEX_USAGE64   /* command line usage error */
       #defineEX_DATAERR65   /* data format error */
       #defineEX_NOINPUT66   /* cannot open input */
       #defineEX_NOUSER67   /* addressee unknown */
       #defineEX_NOHOST68   /* host name unknown */
       #defineEX_UNAVAILABLE69   /* service unavailable */
       #defineEX_SOFTWARE70   /* internal software error */
       #defineEX_OSERR71   /* system error (e.g., can't fork) */
       #defineEX_OSFILE72   /* critical OS file missing */
       #defineEX_CANTCREAT73   /* can't create (user) output file */
       #defineEX_IOERR74   /* input/output error */
       #defineEX_TEMPFAIL75   /* temp failure; user is invited to retry */
       #defineEX_PROTOCOL76   /* remote error in protocol */
       #defineEX_NOPERM77   /* permission denied */
       #defineEX_CONFIG78   /* configuration error */

       #defineEX__MAX         ...  /* maximum listed value */