direnv would have to do too many releases to keep up with all the other project changes

you can take the opportunity of using Python as a corresponding module pexpect is written for it (http://pexpect.sourceforge.net). It's clear that Python language should be installed on the system beforehand

But in all this incongruous abundance you'll certanly find the links to expect It's just what is wanted: the tool, which is traditionally used to communicate automatically with interactive programs. And as it always occurs, there is unfortunately a little fault in it: expect needs the programming language TCL to be present. Nevertheless if it doesn't discourage you to install and learn one more, though very powerful language, then you can stop your search, because expect and TCL with or without TK have everything and even more for you to write scripts.

does not use TCL, Perl, PHP, Python or anything else as an underlying language is written entirely in C has small and simple source code can easily be ported to almost all UNIX-like systems

does not use TCL, Perl, PHP, Python or anything else as an underlying language

It was supposed to be a shell command, not a perl program specified on command line and introducing a dependency on perl.