Filter consecutive lines

• only show the line if the line repeats more than 5 time consecutively

uniq -c text.txt | awk '$1 > 5' | sort | uniq 

single quote vs double quote

• single quotes is literal string, shell won’t identify the special shell symbols like $ and \ in the string.

• e.g. echo '$1' will not work, you have to use echo "$1"

• what about the ‘'? why - is required for both single and double quotes?

sed

use multiple -e arguments to sed the same string multiple times

Shell array

If you want to store multiple arguments in a variable, you can make them a shell array.

Example in config file, you are required to do this: ‘‘‘shell #makepkg.conf #– Command used to run pacman as root, instead of trying sudo and su PACMAN_AUTH=(sudo delayed %c) ’’’

Use parenthesis to create a shell array, which can be appended before other commands. Don’t put the quote the arguments or they will be treated as one single argument.

tee

> cannot be used if the output location requires sudo privilege. Pipe the output to tee instead.