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 ]
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
> echo "hello"
> sleep 2
$ <arrow up> while true; do echo "hello"; sleep 2; done
It's also possible to use sleep command in while's condition. Making one-liner looking more clean imho.
while sleep 2; do echo thinking; done
Colon is always "true":
while :; do foo; sleep 2; done
You can use semicolons to separate statements:
$ while [ 1 ]; do foo; sleep 2; done
You can also make use of
until ((0)); do foo; sleep 2; done
Note that in contrast to
until would execute the commands inside the loop as long as the test condition has an exit status which is not zero.
while read i; do foo; sleep 2; done < /dev/urandom
for ((;;)); do foo; sleep 2; done
Another way using
until [ ]; do foo; sleep 2; done
I like to use the semicolons only for the WHILE statement, and the && operator to make the loop do more than one thing...
So I always do it like this
while true ; do echo Launching Spaceship into orbit && sleep 5s && /usr/bin/launch-mechanism && echo Launching in T-5 && sleep 1s && echo T-4 && sleep 1s && echo T-3 && sleep 1s && echo T-2 && sleep 1s && echo T-1 && sleep 1s && echo liftoff ; done
A very simple infinite loop.. :)
while true ; do continue ; done
Fr your question it would be:
while true; do foo ; sleep 2 ; done