Linux – How to use rsnapshot without remote root

For the first question, there is no salt issue if your shadow file is with $1$FZPUn/2R$JsQCE3TP3Uraez2P8ISIh0 password format (with a dollar, a number, a dollar at the beginning). Because, the salt ils the first part between the next dollars (FZPUn/2R in my example). The crypted password is on the rest. See man crypt, at the 'Glibc Notes' section for details.

So you can move your shadow file without risk.

For the second part, I prefer edit /etc/passwd file directly and change the groupe manualy. Your method is maybe the best (because of lock).

Don't forget files : if you change UID or GID, you must chown each to authorize your user to read his files !

As of GNU coreutils 7.5 released in August 2009, sort allows a -h parameter, which allows numeric suffixes of the kind produced by du -h:

du -hs * | sort -h

If you are using a sort that does not support -h, you can install GNU Coreutils. E.g. on an older Mac OS X:

brew install coreutils
du -hs * | gsort -h

From sort manual:

-h, --human-numeric-sort compare human readable numbers (e.g., 2K 1G)