Bashscripts.org

This is what I have for my cd command: echo "going from $PWD to $1"; cd $1;

Everything works except it doesn't change directories.

This is what I have for my go_back command: echo "going back to $OLDPWD"; cd ~-;

But this is what happens when I run it:

going back to
./go_back: line 1: cd~-: command not found

So I emailed my teacher and this is what he said:

What's going on is, your executing the shell script inside new session instead of the current session.

try putting:

#!/bin/bash

as the first line in your script. This will force it to execute it in the current session. To go back, set up a Global Variable which will hold your past directory, store that directory in the Global Variable before you change directories, in your go_back, just cd to your Global Variable.

I read about global variables and I know how to make them, but I don't really have any experience with them, so I am just a little confused on how to use a global variable to make my two scripts work.

hey,


there must be a space between cd and ~-


I don't know how works putty; and I don't know what "global variables" are (except against local ones in functions).
Bash has some variables that it creates, such as BASH_VERSION, SHELLOPTS, PWD, and so on.

A script always runs in a subshell, it will never change the directory of the main shell.
A script is a child process, it can't change any variable of its parent.

try to add some pwd commands into your script, you'll see it changed directory.
it's the same astyped on the command line: what's between '(' and ')' is executed in a subshell.

Thank you for the help!