SYSEXITS(3) BSD Library Functions Manual SYSEXITS(3)
sysexits -- preferable exit codes for programs
It is not a good practice to call exit(3) with arbitrary values to indicate a failure condition when ending a program. In addition to the
two standard constants in <stdlib.h>, EXIT_SUCCESS and EXIT_FAILURE, the header <sysexits.h> defines few exit codes that can be used as a
parameter to the exit(3) function. By using these constants the caller of the process can get a rough estimation about the failure class
without looking up the source code.
The successful exit is always indicated by a status of 0, or EX_OK. 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 codes is approximately as follows:
EX_USAGE (64) The command was used incorrectly, e.g., with the wrong number of arguments, a bad flag, a bad syntax in a parameter, or
EX_DATAERR (65) The input data was incorrect in some way. This should only be used for user's data and not system files.
EX_NOINPUT (66) 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 (67) The user specified did not exist. This might be used for mail addresses or remote logins.
EX_NOHOST (68) The host specified did not exist. This is used in mail addresses or network requests.
EX_UNAVAILABLE (69) A service is unavailable. This can occur if a support program or file does not exist. This can also be used as a
catchall message when something you wanted to do does not work, but you do not know why.
EX_SOFTWARE (70) An internal software error has been detected. This should be limited to non-operating system related errors as possi-
EX_OSERR (71) 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 returning a user that does not exist in the passwd file.
EX_OSFILE (72) Some system file (e.g., /etc/passwd, /var/run/utmp, etc.) does not exist, cannot be opened, or has some sort of error
(e.g., syntax error).
EX_CANTCREAT (73) A (user specified) output file cannot be created.
EX_IOERR (74) An error occurred while doing I/O on some file.
EX_TEMPFAIL (75) Temporary failure, indicating something that is not really an error. In sendmail, this means that a mailer (e.g.)
could not create a connection, and the request should be reattempted later.
EX_PROTOCOL (76) The remote system returned something that was ``not possible'' during a protocol exchange.
EX_NOPERM (77) 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 (78) Something was found in an unconfigured or misconfigured state.
The numerical values corresponding to the symbolical ones are given in parenthesis for easy reference.
err(3), exit(3), stdlib(3)
The <sysexits.h> header appeared somewhere after 4.3BSD. The manual page for it appeared in NetBSD 4.0.
This manual page was written by Jorg Wunsch after the comments in <sysexits.h>.
The choice of an appropriate exit value is often ambiguous.
March 25, 2010 BSD