Syntax for a single-line Bash infinite while loop

Brian Deacon picture Brian Deacon · Aug 17, 2009 · Viewed 705.5k times · Source

I am having trouble coming up with the right combination of semicolons and/or braces. I'd like to do this, but as a one-liner from the command line:

while [ 1 ]
do
    foo
    sleep 2
done

Answer

Stefano Borini picture Stefano Borini · Aug 17, 2009
while true; do foo; sleep 2; done

By the way, if you type it as a multiline (as you are showing) at the command prompt and then call the history with arrow up, you will get it on a single line, correctly punctuated.

$ while true
> do
>    echo "hello"
>    sleep 2
> done
hello
hello
hello
^C
$ <arrow up> while true; do    echo "hello";    sleep 2; done