Saturday, 30 April 2016

Syntax for a single-line Bash infinite while loop



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



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
$ while true; do echo "hello"; sleep 2; done

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