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.


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.

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

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.
Hide

Tags

Hide

Functions

Commands tagged host from sorted by
Terminal - Commands tagged host - 14 results
getent hosts <host>
dig +short -x 127.0.0.1
10,30,50 * * * * ping -c1 -w3 192.168.0.14 >/dev/null
2012-02-06 14:54:15
User: bashrc
Functions: ping
2

Cleaner with a mailto assignment in crontab (if the command fails you get an email):

MAILTO=admin@example.com

10,30,50 * * * * ping -q -c1 -w3 192.168.0.14 >/dev/null

10,30,50 * * * * ping -q -c1 -w3 192.168.0.14 | grep '1 received' - || mail -ne -s'Host 192.168.0.14 not reachable' admin@example.com
2012-02-06 10:42:46
User: knoppix5
Functions: grep mail ping
-4

Every 20 minutes test if host with IP 192.168.0.14 is 'dead' or not reachable.

The line should be put in your crontab file.

10,30,50 * * * * ping -q -c1 -w3 192.168.0.14 | grep '1 received' - || env DISPLAY=:0 xeyes
2012-02-06 09:40:11
User: knoppix5
Functions: env grep ping
Tags: ping host crontab
-2

Every 20 minutes ping host with IP address 192.168.0.14. If it's not 'alive' or not reachable, then display something eye-catching (here xeyes) on the desktop.

Hint for newbies: edit crontab with

crontab -e
while true; do date; ssh <YOUR HOST HERE> "echo" && echo "HOST UP" && break; sleep 60; done
getent hosts google.com | awk '{print $1}'
2010-11-03 12:02:05
User: depesz
Functions: awk getent
3

has the benefit of being a bit more cross-platform.

host google.com|awk '{print $NF}'
dig hostname a +short
gethostip -d hostname
host foo.com|grep " has address "|cut -d" " -f4
2010-10-29 17:01:37
User: dinomite
Functions: cut grep host
-1

Get just the IP address for a given hostname. For best results, make this a function in your shell rc file so that it can be used for things like traceroute:

Titus:~$ traceroute `getip foo.com`

traceroute to 64.94.125.138 (64.94.125.138), 64 hops max, 52 byte packets

while read n; do host $n; done < list
dig -x 74.125.45.100
2009-09-28 15:13:34
User: postrational
Functions: dig
4

Performs a reverse DNS lookup, variants include:

nslookup 74.125.45.100

or:

host 74.125.45.100
for i in `cat names.txt`; do host -r $i [nameserver]; done
2009-08-22 09:26:31
User: hemanth
Functions: host
Tags: host
0

DNS cache snooping