Basics
Add new changes to the last commit:
git commit FILES --amend (-m "new messages")
See staged changes
git diff --staged
Modify commit and update date
git commit --amend --date="Mon Mar 7 22:40:51 2016 +0800"
GIT_COMMITTER_DATE="Mon Mar 7 22:40:51 2016 +0800" git commit --amend
Delete remote branch at repo origin
git push origin :BRANCH_NAME
reflog helps you recover a deleted branch or a commit deleted by hard-reset:
git log --walk-reflogs # get SHA of the deleted commit
To recover a commit, use
git reset --hard COMMIT_SHA # recover the deleted commit
To recover a branch, use
git branch BRANCH_NAME BRANCH_HEAD_SHA # recover the branch
Work with branch
1. First checkout to a feature branch and work there.
2. Go back to the master branch and make commits.
3. Rebase master in the feature branch.
Create a new branch starting from a commit:
git branch BRANCH_NAME COMMIT_SHA
Some Git log formats:
git log --oneline
git log --oneline --stat
git log --oneline --graph
git log --oneline --patch
Use recursive merge instead of fast-forward merge to keep commits in the feature branch after merging:
git checkout master
git merge --no-ff BRANCH_NAME
Fix line feeds
1. Suppose you have a project of which the contributors work on both Linux/OSX and Windows. On Linux/Cygwin/OSX, you should set
git config --global core.autocrlf input
to fix Windows LFs that get introduced. On Windows, you should set
git config --global core.autocrlf true
to change LF to CR/LF on checkout and convert back to LF on commit. So the line feeds in the project are always LF. When running the Git installer for Windows, you should choose "Checkout Windows-style, commit Unix-style line endings", which automatically sets core.autocrlf to true.
2. Sometimes, your project contains files for both Linux and Windows (e.g., a .NET project with Cygwin bash scripts). In such case, the line-feed conflicts cannot be resolved by simply setting autocrlf. One solution to this problem is to set
git config --global core.whitespace cr-at-eol
This basically tells Git that an end-of-line CR is not an error. As a result, those annoying ^M characters in Windows files no longer appear at the end of lines in
git diff,
git show, etc. Note that extra spaces at the end of a line still show as errors (highlighted in red) in the diff.
Submodules
1. Clone a repo as a submodule of the current repo
git submodule add REPO_URL DIRNAME
cd DIRNAME
git checkout master
2. Note that if we commit changes in a submodule, we also have to commit its parent repo to point to head of the new submodule. Hence, whenever you update a submodule, you need to commit and push twice---one for the submodule and one for its parent repo. To avoid chores, you can do the following in the parent repo:
a) Use
git push --recurse-submodules=check. This option can check whether you have un-pushed submodules. Or
b) Use
git push --recurse-submodules=on-demand. This way submodules that need it will be pushed automatically.
3. To clone a repo that contains submodules, we have to initialize the submodules after clone the repo:
git submodule init
Update the submodules to get the files inside:
git submodule update
Note that each time after you update a submodule, you will be put in a "headless" state, i.e., in a non-existing branch. We have to checkout to a branch (such as master) and do our work there.
