Introduction

Let's face it, we are mere mortals that keep forgetting everytime we learn something new. So that's why I created this simple cheatsheet. Every time I forget something important, I want to refer back in one single place instead of scouring the Internet for the same answer that I did before. Hope this will help.

System magic

Show disk usage

df -h | awk '/^C:\\/ {print $3 "/" $2}'

Show memory used/total

free -h | awk '/^Mem:/ {print $3 "/" $2}'

Show IP and broadcast address

ip addr | grep -m1 inet | sed 's/    //' | sed -e 's/scope global dynamic//g'

Show most memory intensive process

ps axch -o cmd:15,%mem --sort=-%mem

Show most CPU intensive process

ps axch -o cmd:15,%cpu --sort=-%cpu

Show explicit installed packages (from history.log in Ubuntu)

cat /var/log/apt/history.log | grep install | awk '(NR>1)' | sed 's/[^ ]*//' | sed 's/apt install//g' | sed 's/  //'

Sed magic

Remove all double quotes on each line

sed 's/"//g'

Remove everything before the first space

sed 's/[^ ]* //'

Remove last comma on each line

sed 's/,$//'

Remove bracket and everything between a pair of bracket

sed -e 's/\[[^][]*\]//g'

Replace all commas with spaces

sed 's/,/ /g'

Awk magic

Print all column

awk '{print $0}'

Print all line except first

awk '(NR>1)'

Remove empty lines from list result

awk 'NF'

Remove all leading, trailing whitespaces and tabs from each line

awk '{$1=$1};1

Grep specific line numbers

awk 'NR==2{ print; }'

Grep magic

Extract everything inside brackets

grep -oP '\[\K[^\]]+'

Find only first occurence in a file

grep -m1 'searchstring' file_name

Alfins-dev/command-line-magic