When comparing eltclsh vs Eshell (Emacs SHell), the Slant community recommends Eshell (Emacs SHell) for most people. In the question“What are the best Bash replacements?” Eshell (Emacs SHell) is ranked 6th while eltclsh is ranked 11th.
Ranked in these QuestionsQuestion Ranking
Pros
Pro A more consistent alternative to the POSIX shell
Tcl is a saner scripting language built on the same principle as the Unix shell (everything is a string) with more than a hint of Lisp. eltclsh makes it possible to use Tcl interactively with tab completion for both language constructs and file paths. The result is that you can develop a snippet of Tcl code interactively and then paste it in your script.
Pro TclVFS
TclVFS allows you access files inside ZIP archives or on remote HTTP and FTP servers like you would local files. If you put "package require vfs::urltype; vfs::urltype::Mount http"
in your ~/.eltclshrc you can do things like "file copy http://example.com/file /tmp/file" (HTTPS is currently not supported by TclVFS.)
Pro Can invoke almost any elisp function loaded in Emacs
Pro Written in emacs lisp
Cons
Con Stability
eltclsh crashes on mismatched delimiters.