All commands (14,187)

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

for x in `psql -e\l | awk '{print $1}'| egrep -v "(^List|^Name|\-\-\-\-\-|^\()"`; do pg_dump -C $x | gzip > /backups/$x-back.gz
Ran as the postgres user, dumps each database individually. It dumps with the create statements as well, so you can just 'zcat $x-nightly.dmp.gz | psql' to reimport/recreate a database from a backup.

Check for Firewall Blockage.
This is just one method of checking to see if an IP is blocked via IP tables or CSF. Simple and to the point. Replace xx.xx.xx.xx with the IP you wish to check.

list files recursively by size

Should I be sleeping?

Optimal way of deleting huge numbers of files

Output a SSL certificate start or end date
A quick and simple way of outputting the start and end date of a certificate, you can simply use 'openssl x509 -in xxxxxx.crt -noout -enddate' to output the end date (ex. notAfter=Feb 01 11:30:32 2009 GMT) and with the date command you format the output to an ISO format. For the start date use the switch -startdate and for end date use -enddate.

View non-printing characters with cat
Useful to detect number of tabs in an empty line, DOS newline (carriage return + newline). A tool that can help you understand why your parsing is not working.

Determine if photos have been rotated to portrait orientation instead of normal landscape orientation
Most people take photos in landscape orientation (wider than it is tall). Sometimes though you turn the camera sideways to capture a narrow/tall subject. Assuming you then manually rotate those picture files 90 degrees for proper viewing on screen or photo frame, you now have a mix of orientations in your photos directory. This command will print out the names of all the photos in the current directory whose vertical resolution is larger than its horizontal resolution (i.e. portrait orientation). You can then take that list of files and deal with them however you need to, like re-rotating back to landscape for consistent printing with all the others. This command requires the "identify" command from the ImageMagick command-line image manipulation suite. Sample output from identify: $ identify PICT2821.JPG PICT2821.JPG JPEG 1536x2048 1536x2048+0+0 8-bit DirectClass 688KB 0.016u 0:00.006

Compute the average number of KB per file for each dir
Shorter version using --tag

bash pause command
Waiting for a key stroke. You can use this with a ";" behind to build a command chain.


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: