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Google dictionary of word definitions
$ wget -qO - "http://www.google.com/dictionary/json?callback=dict_api.callbacks.id100&q=steering+wheel&sl=en&tl=en&restrict=pr,de&client=te" this does the actual google dictionary query, returns a JSON string encapsulated in some fancy tag $ sed 's/dict_api\.callbacks.id100.//' here we remove the tag beginning $ sed 's/,200,null)//' and here the tag end There are also some special characters which could cause problems with some JSON parsers, so if you get some errors, this is probably the case (sed is your friend). I laso like to trim the "webDefinitions" part, because it (sometimes) contains misleading information. $ sed 's/\,\"webDefinitions.*//' (but remember to append a "}" at the end, because the JSON string will be invalid) The output also contains links to mp3 files with pronounciation. As of now, this is only usable in the English language. If you choose other than English, you will only get webDefinitions (which are crap).

Check your hard drive for bad blocks (destructive)
WARNING!!! ALL DATA WILL BE LOST!!! This command should ONLY be run on drives that are meant to be wiped. Data destruction will result from running this command with the '-w' switch. You may run this command with the '-n' switch in place of '-w' if you want to retain all data on the drive, however, the test won't be as detailed, since the '-n' switch provides a non-destructive read-write mode only, whereas '-w' switch actually writes patterns while scanning for bad blocks.

Check if a process is running
Send signal 0 to the process. The return status ($?) can be used to determine if the process is running. 0 if it is, non-zero otherwise.

find file/dir by excluding some unwanted dirs and filesystems
Consider using this cmd when: 1. You are planning to traverse a big directory. 2. There is a subdir you don't want find to decend to. (entirely ignore) 3. You don't want find to decend to any mounted filesystems under this dir. * The -xdev flag tells find do not go to other filesystems. * -path ./junk_dir -prune is the pattern to ignore ./junk_dir entirely. * The rest is the typical search and print. To ignore multiple subdirs, you can just iterate the pattern, e.g. find . -path ./junk1 -prune -o -path ./junk2 -prune ... If you do want to include other filesystems, then remove -xdev flag. If you want to search files, then change -type d to -type f.

Numeric zero padding file rename
rename file name with fixed length nomeric format pattern

Convert a mp3 file to m4a
I use this to convert mp3 files to m4a files that can be used as ringtones on the iPhone. I've documented the process here: http://www.control-d.com/?p=60

Open a file at the specified line
You may also use +line:column syntax.

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Function to change prompt
Bash function to change your default prompt to something simpler and restore it to normal afterwards.

restoring some data from a corrupted text file
man tac When there is a bad block in the middle of your file, you can see its begninning with `cat' and its end with `tac'. But both commands terminates with an error. So this sequence rebuilds a new file without badblock.


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