Another way to print the last used command in your bash shell.

This very simple trick, prints the last used command in your bash history, with one weird trick.

deusexmachina:~ jason$ echo !!
echo ifconfig | awk '/inet / { print $2 }' | sed -n 2p

To print the shell you are using, this will work very well.

4.4 Mon Jan 14 jason@Yog-Sothoth 0: $ echo $0
/bin/bash

This trick will print the inbuilt set flags for the bash shell.

$ echo $-
himBHs

This is a guide to what they mean.

h: Remember the location of commands as they are looked up for execution. This is enabled by default.
i: interactive
m: Monitor mode. Job control is enabled
B: The shell performs brace expansion (see Brace Expansion above). This is on by default
H: Enable ! style history substitution. This option is on by default when the shell is interactive.

Another very neat Linux trick, I ran ps aux in a terminal, then I re-ran it by getting the command line parameters from the bash history.

4.4 Mon Jan 14 jason@Yog-Sothoth 0: $ ps `echo !!:$`

Not sure how useful this is, but it does work and may be interesting to someone out there.

Another useful trick if a user forgets to use sudo before a very long command, just do this instead.

4.4 Mon Jan 14 jason@Yog-Sothoth 0: $ sudo !!

This will rerun the command line with the sudo prefixed to it.