Edit a file via a script yet maintain the osx tags

Question

On OSX you can have tags which allows you to identify different categories of files. Here are two text files with different tags when viewed in Finder:

I have a large number of these files and have written a bash script to make several edits on these files. So, for instance I do:

$ sed 's/old text/new text/' file1.txt > /tmp/foo.txt
$ cp -p /tmp/foo.txt file1.txt

in which case I get the desired file content but loose the tags:

Question: How do I copy the tags from the original file to the edited file?

Answer 1

When you run > /tmp/foo.txt, you are overwriting the contents of /tmp/foo.txt with the output of sed 's/old text/new text/' file1.txt. Since /tmp/foo.txt doesn't exist when you run this command, bash will create that file for you and then write it.

Then, when you use the -p flag to cp, you are copying the permissions and attributes of /tmp/foo.txt to file1.txt and overwriting it in the process.

Instead, what you want to do is overwrite the contents of file1.txt with the contents of /tmp/foo.txt, which should sound familiar. Run

sed 's/old text/new text/' file1.txt > /tmp/foo.txt
cat /tmp/foo.txt > file1.txt

Note that this doesn't copy any permissions or attributes from file1.txt to /tmp/foo.txt or vice versa - you are maintaining the existing metadata for file1.txt, but modifying the content.

In this specific instance, you could also just use sed -i as pbm suggested.