git-commands.md

Commands

Initialization

mkdir Test
cd Test
ls -a
git init
ls -ltra ./git

By default - Working Directory Name is a Repository Name

git status
git stat

show git tips

touch README.md
git status

UNTRACKED

git add ./README.md - regexp patterns can be used

git status

git commit -m "initial commit" description helps to undestand what's inside this commit, extremly usefull when reading history.

commit HASH - commit ID, if we need to use this commit then ID should be used.

git status

Changing

echo "This is a Test GIT project" > README.txt
git status
git commit -a -m "Added README file content"
git status

Commit here - sends changed file to repo directly (does not work for new files)

History

git log short HASH - stores first 7 digits

git log --pretty=format:"%h %cd %an '%s'"
git log --patch -2

Show differences between commits

Remote branches

origin/master - differences between local version and remote

origin - name can be changed, you can work with different repositories thus many pointers may be used.

git remote show - shows what's happening with remote repo

Merge / Commit

Fast-forward

git checkout -b fix13
git status
touch fix13.txt
git add .
git status
git commit -m "Initial commit of fix13 branch"
git log --pretty=format:"%h %cd %an '%s'"

ls -ltrh - show files in the filesystem for this branch

git checkout master

ls -ltrh - show filesystem again (snapshots)

CAUTION: Do not use branches for content splitting.

git merge fix13 see fast-forward

git log --pretty=format:"%h %cd %an '%s'"

Simple Three-way (recursive)

git checkout -b fix14
echo "It's Fix 14 branch" > fix14.txt
git add .
git commit -m "Initial commit for fix14 branch"

ls -ltrh - file is here

git checkout master - no file here

echo "Two branches was added to this repository" >> README.txt - adding changes

git commit -a -m "Added the second line into README.txt"

git log --graph --oneline --decorate --all

git merge fix14 - editor should appear to insert comment

git log --graph --oneline --decorate --all - cons: history mixed up

One more branch:

git checkout -b fix14
echo "It's Fix 15 branch" > fix15.txt
git add .
git commit -m "Initial commit for fix15 branch"
git checkout master
echo "Fix 15 branch was added to the repository" >> README.txt
git commit -a -m "Added the third line into README.txt"
git checkout fix15
echo "It's a second line for the file" >> fix15.txt
git commit -a -m "Second commit for Fix15 branch"
git checkout master

git log --graph --oneline --decorate --all -7 - two branches master with commit and Fix15 with two commits

git rebase Fix15 - Master << Fix15

git log --graph --oneline --decorate --all -7- solid line instead of two

Previous commit disapeared, new commit added - both of them have same comments.

Why it's recommended not doing rebase ?

First show that all the files exist

ls -ltrh

Answer: previous commit hash disapeared (where HEAD was). If someone has already created branch from this commit. Then we'll have commits without parents. Git allows workarounding this. Good practice is to have a documented procedure how to edit core files.

Git branches

git branch -a
git branch -D fix13 fix14 fix15
git log --graph --oneline --decorate --all

pointers disapeared

Reset

ls -ltrh
rm -f file1*txt
ls -ltrh
git status

git reset --hard HEAD
ls -ltrh
git status

rm -f file1*txt
git commit -a -m "Wrong commit #1"
git log --pretty=format:"%h '%s'" -3

Hard

files removed, commit removed

git reset --hard <HASH>
ls -ltrh
git log --pretty=format:"%h '%s'" -3

Mixed

commit only removed

echo "It's a very important thing" > important1.txt
echo "It's an extremely important thing" > important2.txt
git status
git add important1.txt
git commit -m "Wrong commit #2"
git log --pretty=format:"%h '%s'" -3
git reset <LATEST CORRECT COMMIT HASH>
git log --pretty=format:"%h '%s'" -3

Soft

git add .
git commit -m "Important commit"
git reset --soft <LATEST CORRECT COMMIT HASH>
git log --pretty=format:"%h '%s'" -3
cat important*txt
git status

git commit -m "Important commit 1"
cat README.txt
git log --pretty=format:"%h '%s'"
git checkout <1st COMMIT HASH> README.txt

filesystem remains the same, commits the same, README.txt - replaced

how to return back:

git reset --hard HEAD or git checkout

ls -ltrh
cat README.txt

How to rollback merge

git checkout -b wrng
cat /dev/null > README.txt
cat README.txt
echo "1111" > wrng.txt
git add .
git commit -m "Wrong"
git checkout master
git merge wrng 
cat README.txt
git log --graph --oneline --decorate --all -6

Reflogs git reflog -5 all our actions

git reset --hard HEAD@{1} - rollback by actions

git log --graph --oneline --decorate --all -6 - commits still there, files still there, but fast-forward removed

cat README.txt