Post your *nix trix...

[BigglesPiP]

While I consider myself a GNU/Linux guru, I still learn new things all the time. This is a thread where I'd like you all to post a nifty command/technique you've picked up. Not how to get nVidia dual screen to work, but something small that you use often. There's only one rule; no more than one line of code per post.

I'll start us off:

mv supports embedded substitution, this can be useful when renaming a file:

mv /any/old/file{,.backup}

The substitution is inside the curly braces, replace the bit before the comma (nothing) with the bit after the comma (".backup"). This also works with cp.

 

[BigglesPiP]

I used it to enforce Chrome to start on my second screen which was seemingly impossible otherwise

Another no less correct method is to use the compiz "place window" plugin.





grep can show you lines after and before the matching lines:

user@hostname ~ $ grep -B1 -A2 sometext /any/old/file
hello bob
have you seen sometext anywhere
yes
I have

 

[BigglesPiP]

gotta have the hammer to crack a nut:

Separate a column in a commands output by piping it into awk:

tail /var/log/messages | awk '{print $2}'

The delimiter between the columns is whitespace, but you can set it to anything with the -F parameter on awk.

sed can do this too, but I like awk.

 

[BigglesPiP]

If you're not sure a command worked:

echo $?

0 means it worked, anything else is bad.

 

[BigglesPiP]

the source of my sig text.