sysexits

Description:

sysexits

sysexits.dart #
This is a port from <sysexits.h> promoting standardization of exit codes.
Usage #
This library provides a few constants originally defined in <sysexits.h> for use with dart:io exit() or dart:io exitCode.
import 'dart:io';
import 'package:sysexits/sysexits.dart';

void printUsage() {
print('Usage:');
print('-h, --[no-]help Show help');
}

void main(List<String> argv) {
exitCode = EX_OK; // presume success

for (String arg in argv) {
switch(arg) {
case '-h':
case '--help':
printUsage();
exit(EX_OK);
default:
printUsage();
exit(EX_USAGE);
}
}

print('Do some things');
}
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See (https://dart.dev/tutorials/server/cmdline#setting-exit-codes)
Codes #
It is not a good practice to call exit 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_OK (0) #
successful termination
EX__BASE (64) #
base value for error messages
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 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.
EX__MAX (78) #
maximum listed value
License #
This product includes software developed by the University of California, Berkeley and its contributors.
see LICENSE