Saturday Short Post: Unleashing Daily Productivity with Five Shell One-Liners

Linux users know that the shell itself is a productivity booster on its own. As an old Chinese proverb says: “One shell commands is worth a thousand mouse clicks.”

Here are five one-liners which you can use every day to increase your productivity. I have tested all commands on Ubuntu 20.10 and bash 5.2.

“One shell command is worth a thousand mouse clicks.”

— Old Chinese proverb

1. Pretty-Print a CSV file

CSV files are omnipresent. You can pretty-print them to the terminal via:

Username; Identifier;First name;Last name
booker12;9012;Rachel;Booker
grey07;2070;Laura;Grey
johnson81;4081;Craig;Johnson
jenkins46;9346;Mary;Jenkins
smith79;5079;Jamie;Smith

$ column -s';', -t < your_file.csv

Username    Identifier  First name  Last name
booker12   9012         Rachel      Booker
grey07     2070         Laura       Grey
johnson81  4081         Craig       Johnson
jenkins46  9346         Mary        Jenkins
smith79    5079         Jamie       Smith

2. Convert a UNIX timestamp to a human-readable date

So, what date is 1234567890 again? Just use:

$ date -d @1234567890
Fri Feb 13 23:31:30 UTC 2009

To get the current date and time as a timestamp, run:

date +%s

3. Get all programs which listen on a port

Sometimes, starting an application which needs a port results in a failure. Another application is using this port. Find out which application it is with:

$ lsof -i:yourport

You can get a list of all used ports if you omit the port from the command:

lsof -i

4. Find your public IP address

Speaking of ports, sometimes you need to know what your public IP is. For example, you may have to check if you correctly use the VPN.

The easy way to find it out is:

# Get your IPv6 adress
curl -6 curlmyip.net

# Get your IPv4 address
curl -4 curlmyip.net

5. Remove all files which do not have a given ending

My download folder is often a mess. But what is the easiest way to keep all the important PDFs and EPUBs and get rid of the rest? The following command will do the trick:

rm !(*.pdf|*.epub)

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