Shell Programming and Scripting

I am not able to access the aliases in my environment within a Python script. If I pass the alias to os.system(), I get a message saying "sh: x: not found". I've tried sourcing my .bashrc file in the script, but this does not work. I would perfer not to source my or any rc file because this script should run other user's environments. My script allows me to run commands passed in as arguments, which include aliases to programs, so I can't hardcode any alias values in the program. For example, "myscript grep" would run grep by using os.system() in myscript.
Help would be appreciated.

Thanks.

Aliases are shell constructs; they have to be expanded by the shell. Other languages have no knowledge of them (or have their own aliases).

They are shell constructs, but os.system() invokes the the shell. It is no different than the system() call in Unix. In fact, it probably calls system. That's why I see "sh: x: not found"

It starts a shell, but not necessarily the shell where you defined your aliases.

How can I solve this problem? This seems as if this can happen in any language I use.

You cannot use alias in one shell if it is defined in another. This is independent of any programming language.

Is there a way to send the command to the shell where the script is being executed?