while

Simple shell loop that repeats while the return value remains zero. More information: https://www.gnu.org/software/bash/manual/bash.html#index-while.

• Read stdin and perform an action on every line:

while read line; do {{echo "$line"}}; done

• Execute a command forever once every second:

while :; do {{command}}; sleep 1; done

• Execute a command until it fails:

while {{command}}; do :; done