Porting shell functions to cmd.exe: Is it possible to automatically source scripts on startup?

Question

I'm porting a Linux tool-set that makes frequent use of shell functions to provide certain functionality. These functions are automatically sourced when you start a new shell and include things like changing the working directory, which is nigh impossible with stand-alone programs because child processes can't change their parent's environment.

For example, there is a function cdbm which changes the working directory to one that was previously bookmarked. Now I want to do the same on Windows, but I'm stuck with cmd.exe. As far as I understand the scripts could be ported to jscript, vbscript or plain batch, which shouldn't be a problem. But how do I make sure they automatically get sourced on startup and live in the shell's environment?

Answer 1

According to help cmd:

If /D was NOT specified on the command line, then when CMD.EXE starts, it
looks for the following REG_SZ/REG_EXPAND_SZ registry variables, and if
either or both are present, they are executed first.

    HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\AutoRun

        and/or

    HKEY_CURRENT_USER\Software\Microsoft\Command Processor\AutoRun

As a test, in regedit I created a new key in the HLM branch shown above called "AutoRun" with the string value "echo Hi". When I started a new instance of cmd I got:

Microsoft Windows [Version 6.0.6000]
Copyright (c) 2006 Microsoft Corporation.  All rights reserved.
Hi

C:\Users\Username>

You could put in the name of a script to run instead (I would put in a fully specified path to the script or one with a environment variable in it like "%HOMEPATH%\scripts\scriptname" (including the quotes in case there are spaces in the name).

Edit: The registry key has some side effects. One example is help. If I have the echo command above, for example, in the AutoRun when I type help vol I get a "Hi" right above the help text. Doing vol /?, though doesn't do that.

Answer 2

You can set either of the following registry keys to a batch file or other executable to run that program when CMD is started:

HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\AutoRun
HKEY_CURRENT_USER\Software\Microsoft\Command Processor\AutoRun

A batch file should be able to change the current directory of the executing CMD process with the CD command, as it doesn't run as a subprocess. You can disable the autorun behaviour by supplying /D as a switch to CMD.

See CMD /? for more details.