How to copy symbolic links while preserving the validity of the link?

Question

Say under directory /usr/local/boost_1_52_0/stage/lib, I have a symbolic link: libboost_timer.so, which points to the regular file libboost_timer.so.1.52.0 in the same directory.

How can I cp the symbolic links to directory /usr/local/lib while pointing to the same file /usr/local/boost_1_52_0/stage/lib/libboost_timer.so.1.52.0.

I have searched and tried several options. First one copies the regular file to the destination directory using the name of the link. Second one just copies the link itself, but the link is not valid in the new directory. Third one makes new link points to the original link, so it would de-reference twice to get the regular file. And I want to use the link file name, so directly making the links of the regular file would not work.

How can I do this?

Answer 1

The best way is to dereference twice, but I guess the fact that you mentioned it in your question implies that it isn't any good for your use case (why?).

The second best option you have in a standard bash shell is to use readlink -f (note, this will break if the filename contains trailing newlines, which is extremely unlikely, but possible).

#!/bin/bash
src="$1"
dest="$2"


fileLinkedTo=$(readlink -f "$src")
if [[ -d "$dest" ]]; then
    ln -s "$fileLinkedTo" "${dest%/}/${src##*/}"
else
    ln -s "$fileLinkedTo" "$dest"
fi

And then run it as:

./script /usr/local/boost_1_52_0/stage/lib/libboost_timer.so /usr/local/lib