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

free up memory

Terminal - free up memory
echo 3 > /proc/sys/vm/drop_caches
2012-08-05 19:35:14
User: andreisid
Functions: echo
-4
free up memory

Alternatives

There are 4 alternatives - vote for the best!

Terminal - Alternatives
sync && echo 3 | sudo tee /proc/sys/vm/drop_caches
sync; echo 3 > /proc/sys/vm/drop_caches
sysctl -w vm.drop_caches=3
sudo sync && sudo echo 3 | sudo tee /proc/sys/vm/drop_caches
2012-03-17 08:27:58
User: StephenJudge
Functions: echo sudo sync tee
Tags: memory cache
-1

"That's it. Not much to see here. The first command writes any cache data that hasn't been written to the disk out to the disk. The second command tells the kernel to drop what's cached. Not much to it. This invalidates the write cache as well as the read cache, which is why we have the sync command first. Supposedly, it is possible to have some cached write data never make it to disk, so use it with caution, and NEVER do it on a production server. You could ... but why take the risk?

As long as you are running a post 2.6.16 kernel,..."

Source: http://ubuntuforums.org/showpost.php?p=3621283&postcount=1

Know a better way?

If you can do better, submit your command here.

What others think

Better use sysctl instead of echo :

/sbin/sysctl vm.drop_caches=3o

1 --> to free pagecache

2 --> to free dentries and inodes

3 --> to free pagecache, dentries and inodes

Comment by jlaunay 212 weeks and 2 days ago

Why would calling sysctl be better than calling echo?

Comment by wr8cr8 212 weeks and 1 day ago

There is no big difference but with echo you can make a mistake, for example echo 4 or any bad value will work but sysctl is a tool especially designed to configure kernel parameters:

/sbin/sysctl -w vm.drop_caches=4

sysctl: setting key "vm.drop_caches": Argument invalide

vm.drop_caches = 4

Sysctl also allow you to edit /etc/sysctl.conf to make the change permanent.

Comment by jlaunay 212 weeks ago

Your point of view

You must be signed in to comment.