Properly escaping forward slash in bash script for usage with sed

Question

I'm trying to determine the size of the files that would be newly copied when syncing two folders by running rsync in dry mode and then summing up the sizes of the files listed in the output of rsync.

Currently I'm stuck at prefixing the files by their parent folder. I found out how to prefix lines using sed and how to escape using sed, but I'm having troubles combining those two.

This is how far I got:

source="/my/source/folder/"
target="/my/target/folder/"
escaped=`echo "$source" | sed -e 's/[\/&]/\\//g'`
du `rsync -ahnv $source $target | tail -n +2 | head -n -3 | sed "s/^/$escaped/"` | awk '{i+=$1} END {print i}'

This is the output I get from bash -x myscript.sh

+ source=/my/source/folder/
+ target=/my/target/folder
++ echo /my/source/folder/
++ sed -e 's/[\/&]/\//g'
+ escaped=/my/source/folder/
+ awk '{i+=$1} END {print i}'
++ rsync -ahnv /my/source/folder/ /my/target/folder/
++ sed 's/^//my/source/folder//'
++ head -n -3
++ tail -n +2
sed: -e expression #1, char 8: unknown option to `s'
+ du
80268

Any ideas on how to properly escape would be highly appreciated.

Solution

You don't actually need to bother with escaping the /. From the GNU sed manual:

The / characters may be uniformly replaced by any other single character within any given s command.

For example:

echo 'foobar' | sed -e 's#foo#bar#'

gives the output

barbar

Comments

[Clearer]

This should be the first thing in the man page for sed