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sysexits(3) [osx man page]

SYSEXITS(3)						   BSD Library Functions Manual 					       SYSEXITS(3)

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 arbitrary 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. 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 doesn't work, but you don't know why. EX_SOFTWARE (70) An internal software error has been detected. This should be limited to non-operating system related errors as possi- ble. 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
exit(3), style(9) HISTORY
The sysexits file appeared somewhere after 4.3BSD. AUTHORS
This man page has been written by Jorg Wunsch after the comments in <sysexits.h>. BUGS
The choice of an appropriate exit value is often ambiguous. BSD
March 31, 1996 BSD

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LOCKF(1)						    BSD General Commands Manual 						  LOCKF(1)

lockf -- execute a command while holding a file lock SYNOPSIS
lockf [-kns] [-t seconds] file command [arguments] DESCRIPTION
The lockf utility acquires an exclusive lock on a file, creating it if necessary, and removing the file on exit unless explicitly told not to. While holding the lock, it executes a command with optional arguments. After the command completes, lockf releases the lock, and removes the file unless the -k option is specified. BSD-style locking is used, as described in flock(2); the mere existence of the file is not considered to constitute a lock. If the lockf utility is being used to facilitate concurrency between a number of processes, it is recommended that the -k option be used. This will guarantee lock ordering, as well as implement a performance enhanced algorithm which minimizes CPU load associated with concurrent unlink, drop and re-acquire activity. It should be noted that if the -k option is not used, then no guarantees around lock ordering can be made. The following options are supported: -k Causes the lock file to be kept (not removed) after the command completes. -s Causes lockf to operate silently. Failure to acquire the lock is indicated only in the exit status. -n Causes lockf to fail if the specified lock file does not exist. If -n is not specified, lockf will create file if necessary. -t seconds Specifies a timeout for waiting for the lock. By default, lockf waits indefinitely to acquire the lock. If a timeout is speci- fied with this option, lockf will wait at most the given number of seconds before giving up. A timeout of 0 may be given, in which case lockf will fail unless it can acquire the lock immediately. When a lock times out, command is not executed. In no event will lockf break a lock that is held by another process. EXIT STATUS
If lockf successfully acquires the lock, it returns the exit status produced by command. Otherwise, it returns one of the exit codes defined in sysexits(3), as follows: EX_TEMPFAIL The specified lock file was already locked by another process. EX_CANTCREAT The lockf utility was unable to create the lock file, e.g., because of insufficient access privileges. EX_UNAVAILABLE The -n option is specified and the specified lock file does not exist. EX_USAGE There was an error on the lockf command line. EX_OSERR A system call (e.g., fork(2)) failed unexpectedly. EX_SOFTWARE The command did not exit normally, but may have been signaled or stopped. SEE ALSO
flock(2), sysexits(3) HISTORY
A lockf utility first appeared in FreeBSD 2.2. AUTHORS
John Polstra <> BSD
July 7, 1998 BSD

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