Commands using cat (514)

What's this?

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

Share Your Commands


Check These Out

Mark packages installed with build-dep for autoremove (on Debian/Ubuntu)
Replace PACKAGE with desired package name. Found here: http://mikebeach.org/2011/04/undo-apt-get-build-dep/

floating point operations in shell scripts
using bc is for sissies. dc is much better :-D Polish notation will rule the world...

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Remove duplicate rows of an un-sorted file based on a single column
$F[0] filters using first word. $F[1] - 2nd, and so on.

Doing some floating point calculations with rounding (e.g. at the 3rd decimal)

Convert CSV to JSON
Replace 'csv_file.csv' with your filename.

Get the time since epoch
Get the time since epoch. Useful when working with commands and logs which use this format.

Create a nifty overview of the hardware in your computer
After the command is done, open the html file in a browser

Print number of mb of free ram
Here we instead show a more real figure for how much free RAM you have when taking into consideration buffers that can be freed if needed. Unix machines leave data in memory but marked it free to overwrite, so using the first line from the "free" command will mostly give you back a reading showing you are almost out of memory, but in fact you are not, as the system can free up memory as soon as it is needed. I just noticed the free command is not on my OpenBSD box.

Bypass 1000 Entry limit of Active Directory with ldapsearch
That command bypass the entry limit specifing page results size, when the search arrive to the limit ldapsearch magically reiterate it from the last entry.


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: