get back to the previous location after 'cd' command?
You can simply do
cd -that will take you back to your previous location.
Some shells let you use pushdir/popdir commands, check out this site. You may also find this SO question useful.
If you're running inside a script, you can also run part of the script inside a sub-process, which will have a private value of $PWD.
# do some work in the base directory, eg. echoing $PWDecho $PWD# Run some other command inside subshell( cd ./new_directory; echo $PWD )# You are back in the original directory here:echo $PWDThis has its advantages and disadvantages... it does isolate the directory nicely, but spawning sub-processes may be expensive if you're doing it a lot. ( EDIT: as @Norman Gray points out below, the performance penalty of spawning the sub-process probably isn't very expensive relative to whatever else is happening in the rest of the script )
For the sake of maintainability, I typically use this approach unless I can prove that the script is running slowly because of it.