Git learning notes.

fatal: no files added#

When I add files under a directory using git add some_folder/*, I see the following error message:

The following paths are ignored by one of your .gitignore files:
ppt/__pycache__
Use -f if you really want to add them.
fatal: no files added

This is because * is interpreted by the system, so it will add all files under a directory. If some files under this directory are in the .gitignore, you will see the above error message.

Ref:

• https://stackoverflow.com/q/12084227/6064933

git ask for username and password each time I push#

I cloned a remote repo using https protocol. Each time when I push to this repo, git asks me to enter my username and password. This is annoying.

To prevent from entering username each time, we can add username to remote repo url like this:

git remote set-url origin https://jdhao@github.com/jdhao/toy_project.git

where jdhao is my username. In this way, we do not need to enter username when we push to remote. In fact, we can provide the password after the username like this:

git remote set-url origin https://jdhao:some_pwd@github.com/jdhao/toy_project.git

However, it is not safe to do so, since your password are stored in plain text now.

For password, if we are in Linux, we can use the following settings:

git config --global credential.helper 'cache --timeout=3600'

The password will be cached in memory for 3600 seconds, which means that you do not need to input password for 1 hour. Tweak the time interval to suit your need.

Ref:

• https://docs.github.com/en/github/using-git/caching-your-github-credentials-in-git#platform-linux
• Is there a way to cache GitHub credentials for pushing commits?

Compare same file from different branches#

Sometimes, I want to see the difference of a file on different branches. For example, to find the difference for foo.py on master and dev branch. There are two slightly different ways to do this.

git diff master..dev path/to/foo.py
git diff master dev -- path/to/foo.py

or

git diff master:path/to/foo.py dev:path/to/foo.py

Ref:

• How to compare files from two different branches?

Clone a git repository without history?#

Due to slow networking speed or other reasons, we may want to clone a repository without its huge history. We can use --depth to restrict the number of history to include, --depth 1 will only clone the last commit, effectively meaning that no history is cloned.

git clone --depth 1 http://url/to/git/project

Ref:

• https://git-scm.com/docs/git-clone#Documentation/git-clone.txt---depthltdepthgt
• Clone git repository without history?

How to check last commit for a given line only?#

By default, git-blame will print out the last commit info for each line in a file. What if we are only interested in a particular line range? In this case, we can use -L to restrict the line range. For example, if I want to blame line 4-5 for file options.vim, I can use the following command:

git blame -L 4,5 core/options.vim

Ref:

• Retrieve the commit log for a specific line in a file?