Find The Date That A File Was Added To The Repo

The git log command has a bunch of flags that you can use to filter commits and format their output.

We can get git log to only show the date for a commit in the short format with the following flags:

$ git log --pretty=format:"%ad" --date=short

We can also get git log to filter commits to just those that have files being added:

$ git log --diff-filter=A

Like many git commands, we can restrict the output to those that match a path or file.

$ git log -- README.md

If we put all of these together, then we have a one-line command for getting the date a specific file was added to the repository:

$ git log --pretty=format:"%ad" --date=short --diff-filter=A -- README.md
2015-02-06

See man git-log for more details.