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

about how using internal separate field and store file content on variable

Remove spaces from filenames - through a whole directory tree.
Sometimes, you don't want to just replace the spaces in the current folder, but through the whole folder tree - such as your whole music collection, perhaps. Or maybe you want to do some other renaming operation throughout a tree - this command's useful for that, too. To rename stuff through a whole directory tree, you might expect this to work: for a in `find . -name '* *'`;do mv -i "$a" ${a// /_};done No such luck. The "for" command will split its parameters on spaces unless the spaces are escaped, so given a file "foo bar", the above would not try to move the file "foo bar" to "foo_bar" but rather the file "foo" to "foo", and the file "bar" to "bar". Instead, find's -execdir and -depth arguments need to be used, to set a variable to the filename, and rename files within the directory before we rename the directory. It has to be -execdir and won't work with just -exec - that would try to rename "foo bar/baz quux" to "foo_bar/baz_quux" in one step, rather than going into "foo bar/", changing "baz quux" to "baz_quux", then stepping out and changing "foo bar/" into "foo_bar/". To rename just files, or just directories, you can put "-type f" or "-type d" after the "-depth" param. You could probably safely replace the "mv" part of the line with a "rename" command, like rename 'y/ /_/' *, but I haven't tried, since that's way less portable.

See system users

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

display a smiling smiley if the command succeeded and a sad smiley if the command failed
you could save the code between if and fi to a shell script named smiley.sh with the first argument as and then do a smiley.sh to see if the command succeeded. a bit needless but who cares ;)

Outgoing IP of server
Faster than the curl/wget-approaches.

Watch how many tcp connections there are per state every two seconds.
slighty shorter

File rotation without rename command
Rotates log files with "gz"-extension in a directory for 7 days and enumerates the number in file name. i.e.: logfile.1.gz > logfile.2.gz I needed this line due to the limitations on AIX Unix systems which do not ship with the rename command.

Creating ISO Images from CDs/DVDs
create an iso from your cd/dvd-rom device . You need to umount /dev/cdrom before using the cli

Check a directory of PNG files for errors
Useful for checking if a large number of PNG files was downloaded successfully by verifying the built-in CRC checksum. For incomplete files, the command will print: "00002309.png EOF while reading IDAT data ERROR: 00002309.png" The process is very fast; checking 21,000 files of 5MB in size took only five minutes on a 2011 Intel mobile dual-core.


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: