Most powerful examples of Unix commands or scripts every programmer should know

Question

There are many things that all programmers should know, but I am particularly interested in the Unix/Linux commands that we should all know. For accomplishing tasks that we may

Answer 1

Repeat your previous command in bash using !!. I oftentimes run chown otheruser: -R /home/otheruser and forget to use sudo. If you forget sudo, using !! is a little easier than arrow-up and then home.

sudo !!

I'm also not a fan of automatically resolved hostnames and names for ports, so I keep an alias for iptables mapped to iptables -nL --line-numbers. I'm not even sure why the line numbers are hidden by default.

Finally, if you want to check if a process is listening on a port as it should, bound to the right address you can run

netstat -nlp

Then you can grep the process name or port number (-n gives you numeric).

I also love to have the aid of colors in the terminal. I like to add this to my bashrc to remind me whether I'm root without even having to read it. This actually helped me a lot, I never forget sudo anymore.

red='\033[1;31m'
green='\033[1;32m'
none='\033[0m'

if [ $(id -u) -eq 0 ];
then
    PS1="[\[$red\]\u\[$none\]@\H \w]$ "
else
    PS1="[\[$green\]\u\[$none\]@\H \w]$ "
fi

Those are all very simple commands, but I use them a lot. Most of them even deserved an alias on my machines.