panel 1: shell scripts have a lot of brackets

person: “here’s a cheat sheet to help you identify them all! we’ll cover the details later.

panel 2: (cd ~/music; pwd)

a group of commands. runs in subshell.

panel 3: {cd ~/music; pwd}

a group of commands. runs the same shell.

panel 4: VAR=$(cat file.txt)

run a command & assign output (similar to backticks ``)

panel 5: x=(1 2 3)

creates an array

panel 6: x=$((2+2))

$(()) does arithmetic

panel 7: a{.png,.svg}

expands to a.png a.svg. it’s called “brace expansion”

panel 8: if [ ... ]

[ is a program (aka test) that evaluates statements

panel 9: if [[ ... ]]

[[ is bash syntax. it’s more powerful than [

panel 10: ${var}

another way to reference the variable $var

panel 11: ${var//search/replace}

${...} supports search/replace and lots more fancy things