NAME
sysexits —
preferable exit codes for
programs
SYNOPSIS
#include <sysexits.h>
DESCRIPTION
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
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 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 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 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.
SEE ALSO
err(3),
exit(3),
stdlib(3)
HISTORY
The
<sysexits.h> header appeared
somewhere after
4.3BSD. The manual page for it
appeared in
NetBSD 4.0.
AUTHORS
This manual page was written by
Jörg Wunsch after
the comments in
<sysexits.h>.
BUGS
The choice of an appropriate exit value is often ambiguous.