Tip #4 [bash]: Vim key bindings

If you are a "Vim"er and want to leverage all the might you have in Vim when working in the command line (to navigate, replace, edit and so on), just use vim key bindings!

To do that, in your ./bash_profile (or .bashrc) file, make sure you have the following line:

set -o vim

And you are all set! Happy "viming"!

Tip #3 [sed]: Group capturing

Suppose you have the following text file (let's name it file.txt)

date:2014-01-01 value [10cm]
date:2014-01-02 value [11cm]
date:2014-01-03 value [15cm]
date:2014-01-04 value [19cm]

and you want to strip the date and the numeric vale, like so

2014-01-01 10
2014-01-02 11
2014-01-03 15
2014-01-04 19

You can easily achieve this in the command line using group capturing with sed:

sed -r 's/.*:(....-..-..) value \[(.*)cm\]/\1 \2/g' file.txt

sed captures the first and second group (defined by the use of parenthesis) and prints them out with the identifiers \1 and \2.

The '-r' option allows to use extended regexp expressions. However, this option is usually for Linux distros. If you are using Mac OS X, you will probably have to use the option '-E' instead. If in doubt, check the help by typing man sed.

You can have more information on group capturing with regular expressions here.