bash script regex to get directory path up nth levels

Question

I'm using PWD to get the present working directory. Is there a SED or regex that I can use to, say, get the full path two parents up?

Answer 1

Why sed or regex? Why not dirname:

parent=`dirname $PWD`
grandparent=`dirname $parent`

Edit:

@Daentyh points out in the comments that apparently $() is preferred over backquotes `` for command substitution in POSIX-compliant shells. I don't have experience with them. More info:

http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_06_03

So, if this applies to your shell, you can (should?) use:

parent=$(dirname $PWD)
grandparent=$(dirname $parent)

Answer 2

why not use

"${PWD}/../.."

?

Answer 3

This should work in POSIX shells:

echo ${PWD%/*/*}

which will give you an absolute path rather than a relative one.