Shell flow-of-control syntax


Simple alternative selection:
if command
then commands
else other-commands
fi
Multi-way selection:
case word in
item) commands ;;
esac

item may be a "glob" wildcard match, so *) can be used as a default match
Looping:
while command
do commands
done


for var in list
do commands
done

(var is sequentially assigned to each item in list)

If a command exits with status 0, this is considered "true" for if and while; non-zero status is "false".

The test construct test -option args or [ -option args ] allows for some general conditional tests, such as (but not limited to, see man test):

There are lots of other tests, including logical operators and string or numeric comparisons.

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Steve VanDevender
Last modified: Wed Jul 7 14:38:19 PDT 2004