Hide

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.
Hide

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:

Hide

News

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!
Hide

Top Tags

Hide

Functions

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

'hpc' in the box - starts a maximum of n compute commands modulo n controlled in parallel

Terminal - 'hpc' in the box - starts a maximum of n compute commands modulo n controlled in parallel
c=0; n=8; while true; do r=`echo $RANDOM%5 |bc`; echo "sleep $r"; sleep $r& 2>&1 >/dev/null && ((c++)); [ `echo "$c%$n" | bc` -eq 0 ] && echo "$c waiting" && wait; done
2010-07-08 13:56:28
User: cp
Functions: echo sleep
5
'hpc' in the box - starts a maximum of n compute commands modulo n controlled in parallel

the block of the loop is useful whenever you have huge junks of similar jobs, e.g., convert high res images to thumbnails, and make usage out of all the SMP power on your compute box without flooding the system.

note: c is used as counter and the random sleep

r=`echo $RANDOM%5 |bc`; echo "sleep $r"; sleep $r

is just used as a dummy command.

Alternatives

There are 8 alternatives - vote for the best!

Terminal - Alternatives
echo -n 'targets = $(subst .png,.jpg,$(wildcard *.png))\n$(targets):\n convert $(subst .jpg,.png,$@) $@ \nall : $(targets)' | make -j 4 -f - all
2010-07-15 07:19:17
User: mechmind
Functions: echo make
Tags: batch make
5

this oneliner uses make and it's jobserver for parallel execution of your script. The '-j' flag for make defines number of subprocesses to launch, '-f' tells make use stdin instead of Makefile. Also make have neat flag '-l', which "Specifies that no new jobs (commands) should be started if there are others jobs running and the load is at least load (a floating-point number)."

Also you can use plain Makefile, for better readability:

targets = $(subst .png,.jpg,$(wildcard *.png))

(targets):

echo convert $(subst .jpg,.png,$@) $@

all : $(targets)

Know a better way?

If you can do better, submit your command here.

What others think

wow, good idea!

Comment by simonbarkow 319 weeks and 4 days ago

Your point of view

You must be signed in to comment.