What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again.

Delete that bloated snippets file you've been using and share your personal repository with the world. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

Get involved!

You can sign-in using OpenID credentials, or register a traditional username and password.

First-time OpenID users will be automatically assigned a username which can be changed after signing in.

Universal configuration monitoring and system of record for IT.

Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for:



May 19, 2015 - A Look At The New Commandlinefu
I've put together a short writeup on what kind of newness you can expect from the next iteration of clfu. Check it out here.
March 2, 2015 - New Management
I'm Jon, I'll be maintaining and improving clfu. Thanks to David for building such a great resource!

Top Tags



Psst. Open beta.

Wow, didn't really expect you to read this far down. The latest iteration of the site is in open beta. It's a gentle open beta-- not in prime-time just yet. It's being hosted over at UpGuard (link) and you are more than welcome to give it a shot. Couple things:

  • » The open beta is running a copy of the database that will not carry over to the final version. Don't post anything you don't mind losing.
  • » If you wish to use your user account, you will probably need to reset your password.
Your feedback is appreciated via the form on the beta page. Thanks! -Jon & CLFU Team

Super Speedy Hexadecimal or Octal Calculations and Conversions to Decimal.

Terminal - Super Speedy Hexadecimal or Octal Calculations and Conversions to Decimal.
echo "$(( 0x10 )) - $(( 010 )) = $(( 0x10 - 010 ))"
2009-06-08 19:35:53
User: asmoore82
Functions: echo
Super Speedy Hexadecimal or Octal Calculations and Conversions to Decimal.

^Hexadecimal Ten minus Octal Ten is Eight(in Decimal).

echo "$(( 0xaf )) = $(( 0257 ))"

^Hexadecimal AF and Octal 257 are both Decimal 175.


There are 3 alternatives - vote for the best!

Terminal - Alternatives

Know a better way?

If you can do better, submit your command here.

What others think

The basic point here is that (I'm assuming bash) the shell understands hexadecimal and octal numbers, when strings of digits (0-9,a-f) are preceded by 0x or 0.

Comment by bwoodacre 391 weeks and 2 days ago

That's excellent, which I knew about it sooner!

Comment by nanreh 391 weeks and 2 days ago

Yes, the general idea is that BASH's $(( ... )) construct accepts hex with "0x" and *ASSUMES* numbers with leading zeros are octal. This assumption can cause weird bugs when scripting; especially when time and dates are involved. This produces an error only in the months of August and September:

currentmonth=$( date +%m ) echo "There are $(( 12 - currentmonth )) months left in the year."
Comment by asmoore82 391 weeks and 1 day ago

After some googling, it seems you can force a particular base on an expression via prefixing "base#" to a number. In august/september 'date +%m' will yield 08 and 09, so to fix this the echo would read:

echo "There are $(( 12 - 10#currentmonth )) months left in the year."

to force current month to be interpreted in base 10. Obviously the base must be specified in base 10, although it would be an interesting way to screw up somebody's bash session (if it were possible) to change the default number base. :-)

Comment by bwoodacre 389 weeks and 2 days ago

Your point of view

You must be signed in to comment.