$PWD vs. pwd regarding portability
bash
Solution
POSIX requires `$PWD` to be set in the following fashion:
PWD
This variable shall represent an absolute pathname of the current working directory. It shall not contain any components that are dot or dot-dot. The value is set by the cd utility, and by the sh utility during initialization.
So you can rely on that being set – but do note "... an absolute path...", not the absolute path.
`bash` (at least recent versions) will remember what symlinks you followed when setting `$PWD` (and the `pwd` builtin). `command pwd` (that is, the external command) will not. So you'll get different results there, which might, or might not, be important for you. Use `pwd -P` if you want a path without symlinks.
Do note that the `pwd` documentation states:
If an application sets or unsets the value of PWD, the behavior of pwd is unspecified.
So, don't do that :)
In short, there is no winner here. The environment variable will be there in POSIX shells, as will the external command and possibly a built-in too. Choose the one that best fits your need, the important thing being whether you care about symlinks or not.
Problem
I'm writing a shell script which parses the path of the current working directory (printing a like of all basenames above the current directory). So far, I've been using the environment variable `PWD` to parse the path but I wonder if - I can count on `PWD` to be always set - to give the same result on every platform Would it possibly be better to use the `pwd` shell-builtin? I need this script to run on as many platforms as possible, so I just wondered...