Read sysexits FreeBSD manual page to learn how to use consistent exit codes in shell scripts.
SYSEXITS(3) FreeBSD Library Functions Manual SYSEXITS(3)
NAME
sysexits -- preferable exit codes for programs
SYNOPSIS
#include <sysexits.h>
DESCRIPTION
According to style(9), it is not a good practice to call exit(3) with ar-
bitrary values to indicate a failure condition when ending a program.
Instead, the pre-defined exit codes from sysexits should be used, so 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. Er-
ror 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 whatever.
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 sup-
port 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 possible.
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 in-
cludes 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/utx.active, 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 sys-
tem problems, which should use EX_NOINPUT or
EX_CANTCREAT, but rather for higher level permis-
sions.
EX_CONFIG (78) Something was found in an unconfigured or miscon-
figured state.
The numerical values corresponding to the symbolical ones are given in
parenthesis for easy reference.
SEE ALSO
err(3), exit(3), style(9)
HISTORY
The sysexits file appeared somewhere after 4.3BSD.
AUTHORS
This manual page was written by Jorg Wunsch after the comments in
<sysexits.h>.
BUGS
The choice of an appropriate exit value is often ambiguous.
FreeBSD 13.0 January 21, 2010 FreeBSD 13.0
This is simply amazing!
PDF files for style.0 and sysexits.0 manual pages (4th November 2021).