Bash

The shell itself

Common syntax

I tend to forget it sometimes lol

Brackets

Remember '\[' is a program unto itself. Here are some common flags

Variables

var=55
echo $var

While

while [ condition ]; do
    echo "Hello world"
done

Arays

Fruits={'Apple','Banana','Orange'}

Fruits[0]="Apple"
echo ${Fruits[0]}

declare -A sounds
sounds[dog]="bark"
sounds[cow]="moo"
sounds[bird]="tweet"
sounds[wolf]="howl"

echo ${sounds[dog]} # Dog's sound
echo ${sounds[@]}   # All values
echo ${!sounds[@]}  # All keys
echo ${#sounds[@]}  # Number of elements
unset sounds[dog]   # Delete dog

Math

$((a + 200)) #add 200 to a

Strings

${FOO%suffix} #remove suffix from foo
${FOO#prefix} #remove prefix from foo
${FOO/from/to} #replace first instance of from with to
${FOO//from/to} #replace all instances of from with to
${#FOO} #length of foo

Common tasks

Rename push all .png files through convert

for file in *.png; do
    convert $file "${file%.png}.eps"
done

index