Cygwin shell programming question

Rostfrei · 06-30-2006, 02:59 PM

Hello!

I'm trying out cygwin environment and I have the following problem. I wrote simple script test.sh and chmod it (755) so I will be able to execute it.

It's very simple (test.sh)

Code:

#!/bin/sh
pwd
cd /usr/include/
pwd

I placed it on the root folder (/) and executed it from there:

Code:

$./test.sh

result from scrip:

Code:

/
/usr/include

As you can see everything looks fine. But when script finishes I'm still in the root folder (/) and not in the /usr/include ?!? Why? Everything looks fine in the scope of the shell script, but when it's finished I'm back where I begun.

Best regards,

MensaWater · 06-30-2006, 03:07 PM

The script kicks off a subshell. The cd is occuring in the subshell. Once your script completes it exits the subshell and returns you to your original (parent) shell.

Rostfrei · 06-30-2006, 03:09 PM

Is there anything I can do about it? Some specific way of executing the script? Is this behaviour the same on true linux platform?

Regards,

Rostfrei · 06-30-2006, 03:15 PM

I tried the same thing on VmWare virtual machine (Fedora Core 2) and the behaviour is the same. Not just that. Any exports I make in the shell script are not set anymore after script ends. How can I fix the problem?

MensaWater · 06-30-2006, 03:17 PM

It has the same action in true Linux and Unix. This is the way shells work so is not something with cygwin.

You could do something like "exec /bin/sh" at the end of the script. This WILL leave you in the subshell (actually a replacement of the subshell as that is what exec does - replaces running process with the process following exec). At that point you will be in /usr/include but may not have the environment the way you want it.

Rostfrei · 06-30-2006, 03:23 PM

Ifound the solution. Script has to be executed the following way:

Code:

$. test.sh

So in the command line you write

Code:

<period><white space><shell script>

Regards,

MensaWater · 06-30-2006, 03:36 PM

well duh - of course just "source it" with the dot. Why didn't I think of that?

This is how one gets environment variables from shell scripts into the current shell as well.

Must be late on Friday on a holiday weekend (in the US of course).