(relies on 'imagemagick') This command will convert all .pdf files in a directory into a 800px (wide or height, whichever is smaller) image (with the aspect ratio kept) .jpg. If the file is named 'example1.pdf' it will be named 'example1.jpg' when it is complete. This is a VERY worthwhile command! People pay hundreds of dollars for this in the Windows world. My .jpg files average between 150kB to 300kB, but your's may differ. Show Sample Output

file(1) can print details about certain devices in the /dev/ directory (block devices in this example). This helped me to know at a glance the location and revision of my bootloader, UUIDs, filesystem status, which partitions were primaries / logicals, etc.. without running several commands. See also: file -s /dev/dm-* file -s /dev/cciss/* etc.. Show Sample Output

Bash shortcut to work with the last argument of your last command Show Sample Output

This command is useful if you accidentally untar or unzip an archive in a directory and you want to automatically remove the files. Just untar the files again in a subdirectory and then run the above command e.g. for file in ~/Desktop/temp/*; do rm ~/Desktop/`basename $file`; done

Split File in 19 MB big parts, putting parts together again via cat Nameforpartaa Nameforpartab Nameforpartac >> File Show Sample Output

You can use multiple field separators by separating them with | (=or). This may be helpful when you want to split a string by two separators for example. #echo "one=two three" | awk -F "=| " {'print $1, $3'} one three

Convert all jpegs in the current directory into ~1024*768 pixels and ~ 150 KBytes jpegs

It's works only when you replace '\n' to ONE character.

Just a quick and simple one to demonstrate Bash For loop. Copies 'file' to multiple ssh hosts.

Works in Ubuntu, I hope it will work on all Linux machines. For Unixes, tail should be capable of handling more than one file with '-f' option. This command line simply take log files which are text files, and not ending with a number, and it will continuously monitor those files. Putting one alias in .profile will be more useful.

This is useful when watching a log file that does not contain timestamps itself. If the file already has content when starting the command, the first lines will have the "wrong" timestamp when the command was started and not when the lines were originally written.

This will mv all your mp3 files in the current directory to $ARTIST/$ALBUM/$NAME.mp3 Make sure not to use sudo - as some weird things can happen if the mp3 file doesn't have id3 tags.

(relies on 'imagemagick') Convert all .png files to .gif. This can also go the other way if you reverse the file extensions in the command, e.g.: for file in *.gif; do convert "$file" "$(basename $file .gif).png"; done If the file is named 'example1.png' it will be named 'example1.gif' when it is complete.

When you don't have c_rehash handy. Really simple - if you have a .pem file that doesn't really contain a x509 cert (let's say, newreq.pem), it will create a link, simply called '.0', pointing to that file.

Say you want to execute 'file' on the command 'top' (to determine what type of file it is); but you don't know where 'top' resides: preface the argument with = and zsh will implicitly prepend the path.