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.

If you have a new feature suggestion or find a bug, please get in touch via http://commandlinefu.uservoice.com/

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:



2011-03-12 - Confoo 2011 presentation
Slides are available from the commandlinefu presentation at Confoo 2011: http://presentations.codeinthehole.com/confoo2011/
2011-01-04 - Moderation now required for new commands
To try and put and end to the spamming, new commands require moderation before they will appear on the site.
2010-12-27 - Apologies for not banning the trolls sooner
Have been away from the interwebs over Christmas. Will be more vigilant henceforth.
2010-09-24 - OAuth and pagination problems fixed
Apologies for the delay in getting Twitter's OAuth supported. Annoying pagination gremlin also fixed.

Top Tags



add static arp entry to default gateway, arp poison protection

Terminal - add static arp entry to default gateway, arp poison protection
arp -s $(route -n | awk '/^ {print $2}') \ $(arp -n | grep `route -n | awk '/^ {print $2}'`| awk '{print $3}')
2009-03-25 09:53:10
User: aramosf
Functions: arp awk grep route
add static arp entry to default gateway, arp poison protection


There are 6 alternatives - vote for the best!

Terminal - Alternatives

Know a better way?

If you can do better, submit your command here.

What others think

Careful with this though, especially if it's at a datacenter that are using VRRP. VRRP is *meant* to keep the same MAC address, but some misconfigurations mean it will not.

Comment by dotwaffle 313 weeks and 6 days ago

Handy and interesting but unless you either have a newline after that \ or remove it, you're going to get 'invalid hardware address' back from arp.

Comment by TheMightyBuzzard 313 weeks and 6 days ago

I used postup() in /etc/conf.d/net on my Gentoo box.

On OSX, I had to change it a bit:

arp -s $(netstat -rn | awk '/^default/ {print $2}') $(arp -an | grep `netstat -rn | awk '/^default/ {print $2}'`| awk '{print $4}')
Comment by darkfader 245 weeks and 1 day ago

Your point of view

You must be signed in to comment.