On a Gentoo system, this command will tell you which packets you have installed and sort them by how much space they consume. Good for finding out space-hogs when tidying up disk space.

Useful for deleting old unused log files.

This command will generate "CHECK TABLE `db_name.table_name` ;" statements for all tables present in databases on a MySQL server, which can be piped into the mysql command. (Can also be altered to perform OPTIMIZE and REPAIR functions.)

Tested on MySQL 4.x and 5.x systems in a Linux environment under bash.

Convert comma separated files to tab separated files.

(MySQL eats tab separated files with much less instruction than comma seperated files.)

Limited, but useful construct to extract text embedded in XML tags. This will only work if bar is all on one line.

If nobody posts an alternative for the multiline sed version, I'll figure it out later...

a shorter version

a variation of avi4now's command - thanks by the way!

If your XML is appended to a line with a time stamp or other leading text irrelevant to the XML, then you can append a s/foo/bar/ command, like this:

Just a handy way to get all the unique links from inside all the html files inside a directory. Can be handy on scripts etc.

Save the script as: sort_file

Usage: sort_file < sort_me.csv > out_file.csv

This script was originally posted by Admiral Beotch in LinuxQuestions.org on the Linux-Software forum.

I modified this script to make it more portable.

What happens if there is more than a single space between words, or spaces and tabs? This command will remove duplicate spaces and tabs.

The "-r" switch allows for extended regular expressions. No additional piping necessary.

Note you have also the --xml option ;)

You can replace "sort -nu" with "sort -u" for a word list sorted or "sort -R" for a random-sorted line

(edit: corrected)

GNU Sed can 'address' between two regex, but it continues parsing through to the end of the file. This slight alteration causes it to terminate reading the input file once the STOP match is made.

In my example I have included an extra '/START/d' as my 'start' marker line contains the 'stop' string (I'm extracting data between 'resets' and using the time stamp as the 'start').

My previous coding using grep is slightly faster near the end of the file, but overall (extracting all the reset cycles in turn) the new SED method is quicker and a lot neater.

will show:

installed linux headers, image, or modules: /^ii/!d

avoiding current kernel: /'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d

only application names: s/^[^ ]* [^ ]* \([^ ]*\).*/\1/

avoiding stuff without a version number: /[0-9]/!d

will purge:

only installed apps: /^ii/!d

avoiding current kernel stuff: /'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d

using app names: s/^[^ ]* [^ ]* \([^ ]*\).*/\1/

avoiding stuff without a version number: /[0-9]/!d

This will extract all of the urls from a firefox session (including urls in a tab's history). The sessionstore.js file is in ~/.mozilla/firefox/{firefox profile}

I've been auto-generating some complex GnuPlots; with multiplots the first plot of each group needs to be a 'plot' whereas the others need to be 'replots' to allow overplotting/autoscaling/etc to work properly.

This is used to replace only the first instance of 'replot'.