tcsh (shell) vs Tcl

It's a C-like shell with tenex command-completion feature, which is very convenient.

All the documentation that's needed to use tcsh is located in man tcsh instead of being spread on various helper programs.

Unlike *sh Tcl has a rich standard library.

Unlike in sh you don't need to quote your variable substitutions ('"$1"').
Expanding of arguments occurs mostly explicit and if yet expected in-place (e. g. using eval or subst) it follows strict and well clear rules.
So exec test $argv would execute test with single argument.
And appending {*} before $argv would execute test with all arguments (list expansion).

With a little care you can have the same script work on Linux, *BSD, OS X and Windows.

You can expect a reasonably recent version of Tcl to either installed or available in the repositories of any popular open source *nix.

Tcl can operate at the same level of abstraction as the POSIX shell, which makes it easier to manipulate the output of other programs.

Tcl enables easy deployment through self-contained binaries known as starpacks.

Want to run something 5 times? Here you go: set i 0; time { puts done-[incr i] } 5
If you need real conditional cycle? Not a problem: for {set ready 0; set i 1} {$i <= 100 && !$ready} {incr i} { if {[exec do-some-thing] eq "ready" } {set ready 1} }
Want to measure performance of something or repeat it max 300 times and not longer than 1 seconds? Very simple: timerate { after 20 } 1000 300
How about notifying yourself when some http-server is back online? Sure thing: while {[catch { close [socket localhost 80] }]} { after 1000 }; puts "\7\7\7ONLINE!"
And you can do it also fully asynchronously using events etc.