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
orEX_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
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.