Month: January 2016

Is there a standard or convention that specifies the long-form option negation prefix for a CLI?  That is, which is correct?:

  --nodaemonize
  --no-daemonize

I looked thru the POSIX specs, the Getopt::Long parsers, the manpages for getopt() and getopts(), and found nada!  So what’s a coder to do?  Write a Perl script, of course!  I wrote script that parsed thru the entire man(1) set of pages, and pulled out both forms of negated long options.  Here’s the result:

  Without dash (no):  368 unique options
  With dash (no-):   1135 unique options

And the winner is… BOTH forms!  There is no standard for it. The with-dash form was preferred 3:1, but that’s not enough margin to call it a clear winner.

What was apparent is for a single utility, use ONE OR THE OTHER.  Don’t ever mix them for a single utility.  And there you have it.

== DRAFT ==

Although there’s no need for a standard usage of the getopt() long options, we have only 2 x 26 = 52 available switch characters for the older short options.  (Actually, more, ‘cuz we can do things like -4 or -# or -@ for switches.  Regardless…)

Because choices are limited, a defacto standard has emerged — 30+ years in the making — for the short options:

  -f   --force, sometimes -f is used for a config file
  -h   --help
  -o   --output (to the named file, for example) (rarely: -o optionname=value)
  -v   --verbose
  -q   --quiet

The above are almost universally used, while the following are “frequently” used:

-a    --all or --append; or a start time (the --at-time)
-c    --configuration-file  or related .conf option, sometimes -f is used for this (but -c preferred)
-d    --debug or  sometimes --directory
-D    --no-daemonize or --disable
-e    --error;  send to stderr instead of syslog
-E    --enable
-g    --group(s)
-i    --interactive, --identity or some identity related thing, sometimes --ignore
-l    --long or --lengthy, such as include details (different than verbose); or --log-level, or --list
-n    --count, any numerical thing
-p    --port or --priority
-r    --recursive
-R    --alternate-root or --root, also -R (uppercase) sometimes used for --recursive
-t    time-related things
-T    test related things, especially test timeouts
-u    --user or username or submitter things, sometimes -l used for this (think l = login name)
-V    --version (uses uppercase V because lowercase v means verbose)
-w    a web-related thing, such as a URL
-x and -X    X11 things.  Historically, the upper/lowercase meaning is reversed; 
        lower is disable and upper is enable it -- this is opposite normal convention.
-y    --yes, take the affirmative or default action instead of prompting; also -y used to mean syslog
-z    --colorize-output
-4    IPv4
-6    IPv6
-#    Any numerical limit  (avoid this tho, it causes problems in shell scripts)

And a defacto convention is that the lowercase form is used to invoke an action, while the uppercase form is used to suppress an action.  For example,

 -z (lowercase) typically means to colorize the output
 -Z (uppercase) means to NOT colorize the output, implying it's colorized by default.

But uppercase can also have conventional meanings, too.  Such as -R for an alternate root.

—

These aren’t absolute, and there’s plenty of commands that don’t follow the above, but there’s more that do.  If you’re writing a new utility or command, please try to follow the above!  The community will thank you!