Copy every file in a directory structure into specific path only if file does not exist there already

You can use -u switch from cp command:

copy only when the SOURCE file is newer than the destination file or when the destination file is missing

or use rsync command with --ignore-existing:

skip updating files that exist on receiver

Example:

rsync --ignore-existing source/* destination/

Your original command can be rewritten as:

find . -type f -exec bash -c 'test -e /target-directory/"$1" || cp "$1" /target-directory' sh {} \;

The key here is that we call shell with specific commands and pass found file as $1 argument. If test -e /target-directory/"$1" fails, that means file doesn't exist, in which case cp will copy the file.

In general, one can use other commands, as long as the command can verify existence of a file. Some of the other alternatives:

• /usr/bin/realpath -e /target-directory/"$1" > /dev/null || cp "$1" /target-directory
• stat >/dev/null /target-directory/"$1" || cp "$1" /target-directory/"$1"