Bash

random by max number of case

echo \${RANDOM:0:3}

substitution

• remove dirname

f="./4-Attya-anatomie/expose.pdf"
echo \${f##*/}

expose.pdf

• remove file from dirname

f=/dir1/dir2/file.txt
dirname \$f

/dir1/dir2

• remove extension

file=ra.pdf
echo "\${file:0:-4}"

ra

f="/etc/resolv.conf"
echo "\${f#/etc/}"

resolv.conf

• not determiner fisrt match

f="/etc/resolv.conf"
echo "\${f#*/}"

resolv.conf

interpreted var : eval it

hello=2020
var="hello"
echo \${!var}
# 2020

format string like a table

• select words
• add spaces
• trim spaces: by accept only 14 char

sed 's/\(\(\w\|+\| \)\{14\}\) */\1'