Fix /usr/lib/lib*.so links, in the case you `cp`ed lib folder from a backup (use `rsync -a`, not `cp`!)

fix_lib_links.sh

#!/bin/bash

fix_lib_links() {
	local i j dir write
	[ "$2" = "-w" ] && write="$2"
	dir=${1:-$PWD}
	(
		cd "$dir" && \
		for i in *.so.*; do
			if [ -f "$i" ]; then
				j="$i"
				while [ "${j##*.}" != "so" ]; do
					j="${j%.*}"
					[ -L "$j" ] && break # stop at a link
					if [ -f "$j" ]; then
						# "*.so.0" could be a link to "*.so"
						[ -L "$i" ] && [ "$(basename "$(readlink "$i")")" = "$j" ] && break;
						if diff -q "$i" "$j" > /dev/null; then
							echo "$j -> $i";
							[ -n "$write" ] && ln -sfT "$i" "$j";
							break;
						fi
					fi
				done
			fi
		done
	)
}

find_identic_files() {
	local i j t p q dir write
	[ "$2" = "-w" ] && write="$2"
	dir=${1:-$PWD}
	[ -d "$dir" ] || return 1 # no such folder
	[ -d "$dir/.sha1" ] || mkdir -p -- "$dir/.sha1" || return 2 # can't create .sha1 folder
	[ -d "$dir/.sha1twins" ] || mkdir -p -- "$dir/.sha1twins" || return 3 # can't create .sha1twins folder
	(
		cd "$dir" && \
		for i in *; do
			if [ -f "$i" ] && [ ! -L "$i" ]; then
            	p="$(realpath "$i")"
            	if [ "$(wc -c < "$i")" -eq "0" ]; then
            		t="$dir/.sha1twins/0"
            		if [ ! -e "$t" ] || ! grep -q "$i" "$t"; then
            			echo "$i" >> "$t"
        			fi
        		else
	            	t=$(sha1sum "$p" | cut -d' ' -f1)
	            	j="$dir/.sha1/$t"
	            	q="$(realpath "$j")"
	            	if [ -e "$j" ] && [ "$q" != "$p" ]; then
	            		t="$dir/.sha1twins/$t"
	            		if [ ! -e "$t" ]; then
	            			basename "$q" > "$t"
	        			fi
	            		if ! grep -q "$i" "$t"; then
	            			echo "$i" >> "$t"
	        			fi
	            	fi
	            fi
        		ln -sfT "$p" "$j";
			fi
		done
	)
}

[ $# -gt 0 ] && fix_lib_links "$@"