That's fine. But simple things that should work in order to be painless, don't.

-- -- bash:~]$ if $var < 21; then echo "smaller"; fi

bash: 21: No such file or directory

-- -- BUT this works:

if (( $var < 21 )); then echo "smaller"; fi

smaller

-- -- BUT this DOESN'T:

if [[$var < 21 ]]; then echo "smaller"; fi

bash: 21: No such file or directory

-- -- BUT this DOES (added a space after '[['):

if [[ $var < 21 ]]; then echo "smaller"; fi

smaller

Plus the fact that having to type out 'then' and 'fi' and that semi-colons are semi-necessary are annoying. Compared to today's languages, very little of the non-posix parts of bash feel well though out. We can do better.

All these things make it necessary to understand bash. Most modern programming languages feel familiar. Bash and Sh don't anymore. They feel antiquated.