Changing a shell's current directory with python

[Trent Mick]

[Peter Hansen wrote]
> Andy B. wrote:
> > I've got a python utility that I want to change my shell's current
> > directory based on criteria it finds.  I've scoured google and the
> > python cookbook and can't seem to figure out if this is even possible.
> >  So far, all my attempts have changed the current python session only.
> >  Am I going to have to wrap this in a shell script?
> 
> As you've heard, you can't get there from here.  In fact, even just 
> wrapping with a shell script likely won't be enough, unless you are 
> willing to "source" the script every time you run it.  The only way I 
> know of (and I'd be happy to hear alternatives) to do this in a 
> _transparent_ manner is to combine an alias (which uses "source" for 
> you) with a wrapper script _and_ to have that wrapper script read from 
> some place (stdout or a temporary file or ?) to which the Python script 
> can communicate the desired new environment variables and/or current 
> directory.

I do basically this with a script I have (http://trentm.com/projects/go)
for doing exactly what Andy requested: changing directories.

On Un*x you setup a shell function (like an alias),
which calls the Python script go.py,
which writes a shell script that changes the directory,
which gets 'source'd by the shell function.

    function go () 
    { 
        go_is_on_path="`\which go`";
        if test -e "$go_is_on_path"; then
            export GO_SHELL_SCRIPT=$HOME/.__tmp_go.sh;
            python `\which go` $*;
            if [ -f $GO_SHELL_SCRIPT ]; then
                source $GO_SHELL_SCRIPT;
            fi;
        else
            echo "ERROR: could not find 'go' on your PATH";
        fi
    }

On Windows 'go' does the same thing with a batch file.

Trent

-- 
Trent Mick
TrentM at ActiveState.com