1. awk trick: Find out a network interface’s IP address:
This command displays only the ip of the eth0 interface.
- ip a s eth0 | grep “inet ” | head -n 1 | awk ‘{print $2}’ | cut -f1 -d’/’
$ ip a s eth0 | grep "inet " | head -n 1 | awk '{print $2}' | cut -f1 -d'/'
192.168.8.187
Read more about the iproute2 command here.
2. cp trick: Make a quick copy of a file, with a specified extension:
cp filename{,.copy}
$ cp file1{,.copy}
$ ls file1*
file1 file1.copy
This is good for adding an extension to a file with a very long filename:
$ touch filewithreallylongfilename
$ cp filewithreallylongfilename{,.doc}
$ ls filewithreallylongfilename*
filewithreallylongfilename filewithreallylongfilename.doc
Read more about the cp command here.
3. Runs previous command and replace one string with the another globally (every where it appears):
This runs the previous command, but replaces the “ssh” string with “skel”, globally.
- !!:gs/star/wars
$ cd /etc/ssh/
$ !!:gs/ssh/skel
cd /etc/skel/
Read more about the !! shell trick here.
If you liked this article, read the other oneliner articles here.