true, false and : commands - Bash Full Tutorial

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Infinite Loop `while true; do echo ok done` or `while :; do echo ok done` or `until false; do echo ok done`
Function Return `function positive() { return 0 } function negative() { return 1 }`
Code that will always/never be executed `if true; then echo Always executed fi if false; then echo Never executed fi` Syntax true, : - always return 0 as exit code. false - always returns 1 as exit code.

Infinite Loop

while true; do
    echo ok
done

while :; do
   echo ok
done

until false; do
    echo ok
done

Function Return

function positive() {
    return 0
}

function negative() {
    return 1
}

Code that will always/never be executed

if true; then
    echo Always executed
fi
if false; then
    echo Never executed
fi

Read Article
https://develop.horje.com/learn/1434/reference