while (/bin/true) do echo "Hello, World\!" done
submitted by: email@example.com (Don Garrett)
I would like to point out that the current example for BASH is, while correct, less than exemplary.
In order to better display the advantages bash has over csh-derived shells in command-line usage, I would write this as:while true; do echo 'Hello, World!'; done
This takes advantage of the fact that true is in the user's path, reveals a major advantage bash has over csh (the ability to write one-line loop constructs which are much easier to recall and edit through the command-line history), and uses quotes which can quote the history substitution (!) without the aid of a \.
Of course, if saving characters is the objective, we can write
while true;do echo Hello, World\!;done
And if you want to show off the shell's superior programming capabilities we can get silly:
while true; do echo a; done | sed -e 's/a/Hello World!/'
Of course, if your purpose is readability, rather than jihad, I'd go with a compromise version that has the gratuitous whitespace:
while true; do echo 'Hello, World!' done
You can keep the /bin/true if you wish to illustrate the ability of the while construct to execute an arbitrary pipeline. Or you can go overboard...
while echo blah | grep blah > /dev/null; do echo 'Hello, World!' done
Or you can just
while echo 'Hello, World!' ; do true done
since echo has returned true every time I ever used it. It also has a certain "je ne cest HUH?" when juxtaposed with my first suggestion.
I'm sure I could think up a few more twisted examples, but then whatever point I have left would get buried even deeper.
submitted by: firstname.lastname@example.org (Bob Forsman)