使用 xargs 编写 Bash 脚本来备份文件

Question

I need to copy a file from multiple locations to the BACK UP directory by retaining its directory structure. For example, I have a file "a.txt" at the following locations /a/b/a.txt /a/c/a.txt a/d/a.txt a/e/a.txt, I now need to copy this file from multiple locations to the backup directory /tmp/backup. The end result should be:

when i list /tmp/backup/a --> it should contain /b/a.txt /c/a.txt /d/a.txt & /e/a.txt.

For this, I had used the command: echo /a/*/a.txt | xargs -I {} -n 1 sudo cp --parent -vp {} /tmp/backup. This is throwing the error "cp: cannot stat '/a/b/a.txt /a/c/a.txt a/d/a.txt a/e/a.txt': No such file or directory"

-I option is taking the complete input from echo instead of individual values (like -n 1 does). If someone can help debug this issue that would be very helpful instead of providing an alternative command.

Answer 1

Use rsync with the --relative ( -R ) option to keep (parts of) the source paths.

I've used a wildcard for the source to match your example command rather than the explicit list of directories mentioned in your question.

rsync -avR /a/*/a.txt /tmp/backup/

Answer 2

Do the backups need to be exactly the same as the originals? In most cases, I'd prefer a little compression. [tar](https://man7.org/linux/man-pages/man1/tar.1.html) does a great job of bundling things including the directory structure.

tar cvzf /path/to/backup/tarball.tgz /source/path/

tar can't update compressed archives, so you can skip the compression

tar uf /path/to/backup/tarball.tar /source/path/

This gives you versioning of a sort, as if only updates changed files, but keeps the before and after versions, both.

If you have time and cycles and still want the compression, you can decompress before and recompress after.