Merge two directories recursively

Problem

I want to copy all the contents of a directory (or folder) named source-folder into another directory named destination-folder.

Let’s walk-through an example below.

Assume source-folder contains:

file1.txt
file2.txt
directory1/file3.txt
directory2/file4.txt

And destination-folder contains:

file5.txt
directory1/filexyz.txt
directory2/file4.txt

The final structure I want in destination-folder should be:

file1.txt
file2.txt
file5.txt
directory1/file3.txt
directory1/filexyz.txt
directory2/file4.txt
  • The directory2/file4.txt will be the original that was already in destination-folder, hence ignoring the one from the source-folder.

Solution

An easy solution is to use the rsync command line tool, available in most Linux/Unix systems.

rsync -av --ignore-existing source-folder/* destination-folder/

Without the /* it just copies the source folder itself into the destination! So, you would end up with source-folder under the destination-folder/.

Note: According to https://unix.stackexchange.com/a/149986 the wildcard is not needed, but the trailing slash is.

Detailed explanation

  • rsync: This is the command-line utility used for synchronizing files and directories between different locations, either on the same system or between different systems.
  • -av: Combines the following two options:
    • -a (or --archive): This option is used to achieve archive mode, which is essentially a combination of several other options like -r (recursive), -l (copy symlinks as symlinks), -p (preserve permissions), -t (preserve modification times), and more. It’s a convenient way to ensure that files are copied with their metadata and properties preserved.
    • -v (or --verbose): This option enables verbose mode, meaning that rsync will display detailed information about the files being transferred and the progress of the synchronization.
  • --ignore-existing: This option tells rsync to skip copying files that already exist in the destination folder. If a file with the same name exists in the destination, it won’t be overwritten or updated.

August 13, 2023