* [[$PWD vs. pwd regarding portability|https://stackoverflow.com/questions/10795014/pwd-vs-pwd-regarding-portability]] --- `$(pwd)` has issues with paths with newline chars, `$PWD` is fine but can be wrongly reset by badly-made programs; all appear to be available on all good shells.
* [[How to find the last field using 'cut'|https://stackoverflow.com/questions/22727107/how-to-find-the-last-field-using-cut]] --- `echo 'maps.google.com' | rev | cut -d'.' -f 1 | rev`
