"seq 100" outputs 1,2,..,100, separated by newlines. awk adds them up and displays the sum.

"seq 1 2 11" outputs 1,3,..,11.

Variations:

1+3+...+(2n-1) = n^2

1/2 + 1/4 + ... = 1

Leading zeros might help correct sorting and they can be removed by sed after sorting

Does not necessarily require a file to process, it can be used in a pipe as well:

I don't remember where I copy/pasted this from, I wish I credited the original author

Replace < pw-length > with the desired password-length.

The password-length is not always correct, but wayne...

verifry if link detected or no and speed of network.

-N removes header

-s removes separator chars

-r raw output

After using these options, the MySQL ouptut can be used with pipes very easily

Most people know that you can run a PHP script from the command line like so:

But sometimes I just want to run a quick bit of code, the PHP Command Line Interface allows me to do so with the -r option.

Requires package php5-cli

Useful to detect number of tabs in an empty line, DOS newline (carriage return + newline).

A tool that can help you understand why your parsing is not working.

man -t manpagename gives a postscript version of said man page. You then pipe it to ls, and assuming you have cups set up, it prints in your default printer.

The file .my.cnf located at user's home directory is used for mysql login. If this file exists, then

can be replaced with

It saves you from typing!

This is valid for mysqladmin and mysqldump commands as well.

I needed to get a feel for how "old" different websites were, based on their directories.

Xsane produces PDFs that are too large - particularly multipage PDFs. This command compresses them. If you do not use A4, remove the -sPAPERSIZE flag.

I recently found myself with a filesystem I couldn't write to and a bunch of files I had to get the hell out of dodge, preferably not one at a time. This command makes it possible to pack a bunch of files into a single archive and write it to a remote server.

host is a simple utility for performing DNS lookups. It is normally used to convert names to IP addresses and vice versa. When no arguments or options are given, host prints a short summary of its command line arguments and options.

bc is a wonderful calculator. Just type bc at the command line and have at it. Ctrl+D (or type quit) will get you out. This usage is just scratching the surface: bc can handle a mini scripting language, complete with variable, statements, loop, conditional statements and more. Do a man page on it to find out.

Short and sweet command. This command is also useful for other information such as what IP address a particular user logged in from, how long had they been logged in, what shell do they use.