There have been a variety of UnixShells for a long time (see QuarterCenturyOfUnix).
During that long time, computers have increased in speed perhaps a millionfold. What was once way too slow is now done in the blink of an eye.
There are two major command interpreter code forks in Unix: the BourneShell and the CeeShell. Here's an example that will email all your files to someone else:
BourneShell: /bin/sh, ksh, bash, and others
address=c2.7.CspamGarrod@SpamGourmet.com
export address
for i in *
do
mail -s $i $address <$i
done
CeeShell: csh, tcsh, and others
setenv address c2.7.CspamGarrod@SpamGourmet.com
foreach i ( * )
mail -s $i $address <$i
end