GIT Commands reference for DevOps Engineer

Dear DevOps Engineer!! this post is full of experimenting with git commands running most of them on the 'Git Bash' window in my laptop. I've collected three things about each git command.

• git command syntax
• What this git command will do - short descriptions
• An example command that I've executed
• Screenshot of that command execution

How do I Start a Fresh repository in Git CLI(local repo)?

You need to create a folder where you would like to start your coding project. The code can be web-site related where you can have multiple directories involved such as HTML files into a folder, all images to be used in the website in a folder, CSS files into a folder, etc. First, make the folder structure for you project then at the root of the project need to initialize the project.  To create empty repo or re-initializing a repo

Syntax :

git init

Note: It is always better to have a fresh directory created and then run the above command to initialize a local Git repository.

git init example

Getting a remote repository to your git client - Local system/Laptop

You can have the remote repository either public or private teams on the following SCM clouds:

1. GitHub 
2. GitLab
3. BitBucket

git clone Syntax:

git clone ssh://git@github.com/[username]/[repository-name].git

Create a local copy of a remote repository of GitHub or Gitlab. Make sure that you're doing first time in that folder, it should not have the same repo that means if your re-run the same command it cannot work.

Please make sure you have the correct access rights and the remote repository exists

Example of using gitlab URL:

 git clone https://github.com/BhavaniShekhar/vtdevops2021feb.git

Vybhava : git clone 

Syntax:

git commit -m "[commit message]"

commit changes
Example:

git commit -m "some message"

git commit command

Syntax:

git checkout -b [branch name origin/[branch name]

Clone a remote branch and switch to it
Example:

git checkout -b feature2

Differences between git checkout & switch command

Syntax:

git checkout [branch name]

Switch to a branch
Example:

git checkout

git checkout command

Syntax :

git checkout -

Switch to the branch last checked out
Example :

git checkout -

git last checkout command

Syntax:

git checkout -- [file-name.txt]

Discard changes to a file on which you are worked recently.
Example:

Syntax:

git push origin [branch name]

push to a branch to your remote repository
 Example:

git push origin slave

git push command

Syntax:

git push -u origin [branch name]

push changes to remote repository (and remember the branch)
Example:

git push -u origin feature1

git push origin command

Syntax:

git push

push changes to remote repository (remembered branch)
Example:

git push

git push command 

Syntax:

git push origin --delete [branch name]

delete a remote branch
 Example:

git push origin --delete feature3

git remote branch delete oush command

git pull command

Syntax:

git pull origin [branch name]

update local repository to the newest commit
Example:

git pull

git pull command

pull changes from remote repository Example:

git pull origin newbranch2

git remote

Syntax:

git remote add origin ssh://git@github.com/[username]/[repository-name].git
    or
 git remote set-url origin ssh://git@github.com/[username]/[repository-name].git

add a remote repository Example 1:

git remote add origin git@gitlab.com:gitops4/docker-exercises.git

set a repository's origin branch to ssh Example 2:

git remote set-url origin git@gitlab.com:gitops4/docker-exercises.git

git log

The syntax for the git log command is:

git log [--summary] [--oneline]

view changes
Example:

git log

git log command

view changes made to files or directory in (detailed)
Example:

    git log --summary

git log summary command

view changes(briefly)
Example:

    git log --oneline

git log oneline command

Syntax:

git diff [source branch] [target branch]

preview changes before merging 

References: 

 Git log command examples https://www.thegeekstuff.com/2014/04/git-log/

Git File Lifecycle

In this post, we will explore, experiment and see git basic files and folder-related commands if you are familiar with the Linux file system this will be easy for you! But, again no need to worry about that we will see every command execution with experiments.

Every software product/server Lifecycle can be visible with their STATUS output, where they are currently if you know then you can move to different Lifecycle state. Let's understand how this navigation happens on the Git repository.

Git File lifecycle status changes with commands

Git Status

Git Status will always compare the files and folders with the indexed with untracked files and display their status. 

Syntax:

git status [options]

This command will check the status of the current branch by comparing it with the master branch
Example:

git status -s 

This `git status` command will show the working tree status. and it is having multiple useful options.

When you use the -s or --short option it will display the concisely where status will be represented with single alphabet 

1. ' ' = unmodified
2. M = modified
3. A = added
4. D = deleted
5. R = renamed
6. C = copied
7. U = updated but unmerged

In the help page you can find more details about different format output meanings in three different tables.
 

Adding files and folders to the Stage area

We can add files from the work area to the stage area using the `git add` command. 

git add command

Here we can add TEXT files because all program codes will be ASCII text format only.

Syntax:

git add [file-name]

this files can be recently modified shell or python program using some editor.

Add a file to the staging/index area

Example:

 git status # shows nothing
 vi public/product.html # create a file and edit then save it.
 git status # observer it shows red color output.
 git add public/product.html
 git status # shows the changes in green     
   

Adding file to Git repository (local)

Adding entire folder 

You are working on a website project you need to add all the images files (.jpg) required for your website are need to place into a folder called 'images'.  To send from Untracked state files to tracked level or you can say this as work-copy to index area entire folder you can send by providing foldername as argument to git add command.

clear
cd source_code
mkdir images css publish
cd images
#copy some images to images directory here for learning used touch filename.jpg used
cd ..
git add images 

Git add entire folder example

When you observer the the staged files now the two image files will be in green colored that indicates that they are moved to index area of Git repo.

After adding folder status

Adding Current folder content

Similar to Unix/Linux  uses dot to indicate current folder content it may contain

Git add with current directly

Syntax:

git add -A

Adding all folders all files -A

add all new and changed files to the staging area

Git add All Folder

Example:

git add -A

Removing files and directories from repository

Now this can be in three use cases. 

Use case 1: let's see how to remove a file or directory from local repository and also from the filesystem

git rm testcode.file [code-dir] -f

Remove files from git repository

  git rm publish/product.html # Errors out
git rm -f publish/product.html 
git status 
cd publish; ls # file removed from the filesystem as well
  

Use case 2: removing a file or directory from local repo and not from filesystem

git rm testcode.file [code-dir] --cached

Use case 3: removing a file or directory display a trail run, not really deletes anything from the repository.

git rm testcode.file [code-dir] –dry-run

Check the list of files changed

There are lots of options to check this with git and subcommands Here we will see with ls-files option so that you can see the list of files or folders recently changed

 git ls-files 

List of files in single line space separated

 git ls-files –z 

This is another wonder option with -d , where Git will lists the files or folders which are last delated from the existing repository.

git ls-files -d

Renaming file using git mv

Similar to LInux mv command we can rename a file or folder using git mv command. Here we can have existing file or folder and renamed to new file name or folder. After this if we check the status in short it will shows 'R' that means Renamed.

git mv publish/index.html publish/sanjay.html
git status -s -b

Hope you enjoyed this post of learning love on GitOps!!! Yom be interested in the next git learning post on git branching.

Git branching - local and remote

Hello all, in this post specially dedicated to all DevOps/DevSecOps Engineers.  Where their daily routine will have this commands if we know these we can play with them easily if you don't then it will be horrifies you! 

Git Branching explained in detailed

Prerequisites to this you should be aware git basics and to experiment with these command examples should have git installed on your Mac/Linux or git bash on Windows system.

What is the Branch in Git?

A Git branch is a separate line of work, where your work will not disturb other DevOps team members work.

Branch is a simply a movable  pointer to commit, this we can observe using git branch command output wherever you see that '*' prefixed there the pointer pointing. Default branch is master or main (new trend) but it is optional we can name anything when we initiate the git repository.

Main branch is the FIRST branch of your project that means once you run the 'git init' then 'git branch' you can observe this.

On the branch we can have many changes until find the solution and accordingly you need to do multiple commits.

Each branch created for different purpose for example new feature development we name them as 'feature'. similarly we can also have planned releases where we name them as 'release1.0' or 'dev-release'. Again it is flexible to the SCM manager decision.

Why we need to create branch in Git?

The Major reasons for Git branching are:

• Any new features development could BREAK the code, to save this.
• No disturbance between two developer codes that means this git branching simplify the collaboration work which gives more agility to the project

Gitting Start Branching

Here I'm with an interesting story about SCM Git branching that helps to work in collaborative environments where DevOps is a culture.

Let me share with you guys about the steps that I've executed in this are realtime requirements.

Top 10 Examples on git branch sub-command 

1. How to create a branch and check using git sub-commands?

To create a new branch from the existing branch. Here you should be on one of the branch. Generally we start from main or master branch.

git branch newbranch
git branch

2. How to jump onto the new branch directly when it is created?

Create a branch and switch to it in single command

git checkout -b feature
git branch

3. How to switch between the git branches?

Switch to branch We have two command options for switching between branches. 

a. Regular subcommand for switching to a branch

git checkout newbranch
git branch

b. New way to switch between the branch

git switch master
git branch

5. How can I view all local repo branches? 

To view all branches which are created in the local repository no option will do or else we can use status with -b to see in single-line output

git branch 
git status -b -s #alternative option

6. How can I see remote branches on my local laptop/local repo?

To view all the remote branches only you need to use -r or --remote as options

This is command will help you to get more info about all the branches are available in the remote git server such as GitHub or BitBucket etc.
 

git branch -r 
git branch --remote 

git branch remote to view your github or bitbucket branches

7. How can I see all local and remote repositories together?

To view all branches including remote branches use -a or --all options 

git branch -a 
git branch --all 

Observe the different colors for each repos.

1. The green color indicates current working tree(branch)
2. The red indicates remote repo branches
3. The white color indicate local branches

git branch all command example

8. Is there any way to delete a git branch in local repo? 

Delete a branch can be allowed when we use the -d or --delete options on a target branch.

Note : You cannot delete the branch on which you are working. Switch to anyother branch then run this.

git branch -d newbranch
git branch --delete newbranch

Removing a branch

[This is best option to delete because it preserves the recent changes made on the local branch] 9. Deleting the remote branch This is delicated operation, double check before you run this command.

git branch -D myremote-branch 

Compare -d and -D example for git branch removal

9. How to delete a remote branch in git command line ?

Better option is to use delete option with push command

git push origin --delete myremote-branch

10. How to rename a branch on git?

Move a branch/Rename 

a. Linux move command used to rename same way here a branch can be renamed and its reflog

git branch -m newbranch dev
git branch --move newbranch dev 

Git branch move or renaming

b. Rename forcefully 

Even though your target branch exist the git move will happen forcefully when we use -M option.

git branch -M newbranch dev

Hope you enjoy this story. Connect with our earlier technical articles might give some new tricks or tips for your project growth and more productive.

Cheers!!

Git log - commit history

Here is the GitOps story! we started learning more depth of every GIT commit history using git CLI. In this post, we have touched some rea-time scenario-based question and answers with practical examples which are useful for other DevOps team members. 

The best question to help release management - who worked on the critical program/script which is in the release process? This can be found using the git log command. 

The most interesting story if someone left the company and need to know what he did in his last commit. Tracking changes all of them done by that particular user. 

The git log having many options:

1. sorting
2. filtering
3. output formatting

Let's see in detail by with experimenting each with an example.

How to get the git log in a "Sorting order"?

Here we have a couple of sorted commit history commands. 

Using the --pretty value with Oneline to going to give you the log output in simplify format.

git log --pretty=oneline
  

The output combination of COMMIT_ID COMMIT_MESSAGE | Branch level changes

How to do Filtering while getting the git-log output?

To filter out we can use different options

1. author - User name of the commit made by
2. date ranges - We have date options with --before and --after where date can be given in "YYYY-MM-DD" format
3. regular-expressions - Linux grep like option --grep that takes any text patter to filter 
4. path - file or directory path can be used to narrow down your log filtering
5. 
   

Find the commit history of a user

Here we have an option to get all changes made by a person/author. If you want to see all commits made by yourself then you can replace the "AUTHOR NAME" with your git user. name what you have configured. 

git log --author="AUTHOR NAME"

For example: Find all code changes done by user "Rajasekhar"

Find History in range of dates

You have a choice of selecting range of date before and after dates.

git log --before="date1" --after="date2"

For example: Find all commits between 19th Feb to 26th Feb 2021

Commit History with a regular expression

Git commit history can be extracted with the regular expression that matches to the word or pattern that matches the existing commit messages.

git log --grep="PATTERN"

For example, find all the 'commit's having an "adding" pattern.

 

Commit history of a given path

We can use the current work-tree contained in any one of the folders as the path to check the history of that particular directory.

git log -- [PATH]

Example for finding the git log history of file of folder as shown below:

git log -- . # current folder
git log -- WebLogic/samples # specific directory history
git log -- README.md # specific file history  

what is happening in this directory?

Knowing about a particular code file we can use -- then the filename.

For example; 

Commit History of a file

What happened since the date?

Changes from a particular "date" onwards we can get using --since option.

git log --since="YEAR-MM-DD"

For example, find all change that happen since 22-Feb-2021

Since date onwards commit changes

In most of the real scenarios we need to know the files which are changed recently. This git-log command with the oneline option and abbreviated commit id helps us to have a simple view

git log --pretty=oneline --abbrev-commit  

git log command with --abbrev-commit to short commit-id output

You can use this for more combinations as per your project requirements To get all oneliner logs with short commit id and filtered with specific author changes:

git log --pretty=oneline --abbrev-commit --author "Bhavani" 

To get all oneline logs with short commit id for all changes made for "WebLogic" pattern matched in the commit messages.

git log --pretty=oneline --abbrev-commit --grep "WebLogic" 

Further learning post:

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