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Calculate pi to an arbitrary number of decimal places
Change the scale to adjust number of decimal places prefix the command with "time" to benchmark the computer (compare how long it takes to calculate 10000 digits of pi on various computers).

dd with progress bar and statistics to gzipped image
This is a useful command to backup an sd card with relative total size for piping to pv with a progressbar

Send an email from the terminal when job finishes
Might as well include the status code it exited with so you know right away if it failed or not.

search for a file in PATH
Also searches for aliases and shell builtins

defragment files
Thanks to flatcap for optimizing this command. This command takes advantage of the ext4 filesystem's resistance to fragmentation. By using this command, files that were previously fragmented will be copied / deleted / pasted essentially giving the filesystem another chance at saving the file contiguously. ( unlike FAT / NTFS, the *nix filesystem always try to save a file without fragmenting it ) My command only effects the home directory and only those files with your R/W (read / write ) permissions. There are two issues with this command: 1. it really won't help, it works, but linux doesn't suffer much (if any ) fragmentation and even fragmented files have fast I/O 2. it doesn't discriminate between fragmented and non-fragmented files, so a large ~/ directory with no fragments will take almost as long as an equally sized fragmented ~/ directory The benefits i managed to work into the command: 1. it only defragments files under 16mb, because a large file with fragments isn't as noticeable as a small file that's fragmented, and copy/ delete/ paste of large files would take too long 2. it gives a nice countdown in the terminal so you know how far how much progress is being made and just like other defragmenters you can stop at any time ( use ctrl+c ) 3. fast! i can defrag my ~/ directory in 11 seconds thanks to the ramdrive powering the command's temporary storage bottom line: 1. its only an experiment, safe ( i've used it several times for testing ), but probably not very effective ( unless you somehow have a fragmentation problem on linux ). might be a placebo for recent windows converts looking for a defrag utility on linux and won't accept no for an answer 2. it's my first commandlinefu command

check open ports without netstat or lsof

See a full list of compiler defined symbols
From http://lists.debian.org/debian-devel/2001/01/msg00971.html .

show the date every rpm was installed
the newest rpms are at the top; individual packages can also be queried this way: rpm --last -q package

Unaccent an entire directory tree with files.
This command changes all filename and directories within a directory tree to unaccented ones. I had to do this to 'sanitize' some samba-exported trees. The reason it works might seem a little difficult to see at first - it first reverses-sort by pathname length, then it renames only the basename of the path. This way it'll always go in the right order to rename everything. Some notes: 1. You'll have to have the 'unaccent' command. On Ubuntu, just aptitude install unaccent. 2. In this case, the encoding of the tree was UTF-8 - but you might be using another one, just adjust the command to your encoding. 3. The program might spit a few harmless errors saying the files are the same - not to fear.

Get a range of SVN revisions from svn diff and tar gz them
Handy when you need to create a list of files to be updated when subversion is not available on the remote host. You can take this tar file, and upload and extract it where you need it. Replace M and N with the revisions specific to yours. Make sure you do this from an updated (svn up) working directory.


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