Category: git

Git – Commit Changes ”; Previous Next Jerry has already committed the changes and he wants to correct his last commit. In this case, git amend operation will help. The amend operation changes the last commit including your commit message; it creates a new commit ID. Before amend operation, he checks the commit log. [jerry@CentOS project]$ git log The above command will produce the following result. commit cbe1249b140dad24b2c35b15cc7e26a6f02d2277 Author: Jerry Mouse <[email protected]> Date: Wed Sep 11 08:05:26 2013 +0530 Implemented my_strlen function commit 19ae20683fc460db7d127cf201a1429523b0e319 Author: Tom Cat <[email protected]> Date: Wed Sep 11 07:32:56 2013 +0530 Initial commit Jerry commits the new changes with — amend operation and views the commit log. [jerry@CentOS project]$ git status -s M string.c ?? string [jerry@CentOS project]$ git add string.c [jerry@CentOS project]$ git status -s M string.c ?? string [jerry@CentOS project]$ git commit –amend -m ”Changed return type of my_strlen to size_t” [master d1e19d3] Changed return type of my_strlen to size_t 1 files changed, 24 insertions(+), 0 deletions(-) create mode 100644 string.c Now, git log will show new commit message with new commit ID − [jerry@CentOS project]$ git log The above command will produce the following result. commit d1e19d316224cddc437e3ed34ec3c931ad803958 Author: Jerry Mouse <[email protected]> Date: Wed Sep 11 08:05:26 2013 +0530 Changed return type of my_strlen to size_t commit 19ae20683fc460db7d127cf201a1429523b0e319 Author: Tom Cat <[email protected]> Date: Wed Sep 11 07:32:56 2013 +0530 Initial commit Print Page Previous Next Advertisements ”;

Git – Managing Branches ”; Previous Next Branch operation allows creating another line of development. We can use this operation to fork off the development process into two different directions. For example, we released a product for 6.0 version and we might want to create a branch so that the development of 7.0 features can be kept separate from 6.0 bug fixes. Create Branch Tom creates a new branch using the git branch <branch name> command. We can create a new branch from an existing one. We can use a specific commit or tag as the starting point. If any specific commit ID is not provided, then the branch will be created with HEAD as its starting point. [jerry@CentOS src]$ git branch new_branch [jerry@CentOS src]$ git branch * master new_branch A new branch is created; Tom used the git branch command to list the available branches. Git shows an asterisk mark before currently checked out branch. The pictorial representation of create branch operation is shown below − Switch between Branches Jerry uses the git checkout command to switch between branches. [jerry@CentOS src]$ git checkout new_branch Switched to branch ”new_branch” [jerry@CentOS src]$ git branch master * new_branch Shortcut to Create and Switch Branch In the above example, we have used two commands to create and switch branches, respectively. Git provides –b option with the checkout command; this operation creates a new branch and immediately switches to the new branch. [jerry@CentOS src]$ git checkout -b test_branch Switched to a new branch ”test_branch” [jerry@CentOS src]$ git branch master new_branch * test_branch Delete a Branch A branch can be deleted by providing –D option with git branch command. But before deleting the existing branch, switch to the other branch. Jerry is currently on test_branch and he wants to remove that branch. So he switches branch and deletes branch as shown below. [jerry@CentOS src]$ git branch master new_branch * test_branch [jerry@CentOS src]$ git checkout master Switched to branch ”master” [jerry@CentOS src]$ git branch -D test_branch Deleted branch test_branch (was 5776472). Now, Git will show only two branches. [jerry@CentOS src]$ git branch * master new_branch Rename a Branch Jerry decides to add support for wide characters in his string operations project. He has already created a new branch, but the branch name is not appropriate. So he changes the branch name by using –m option followed by the old branch name and the new branch name. [jerry@CentOS src]$ git branch * master new_branch [jerry@CentOS src]$ git branch -m new_branch wchar_support Now, the git branch command will show the new branch name. [jerry@CentOS src]$ git branch * master wchar_support Merge Two Branches Jerry implements a function to return the string length of wide character string. New the code will appear as follows − [jerry@CentOS src]$ git branch master * wchar_support [jerry@CentOS src]$ pwd /home/jerry/jerry_repo/project/src [jerry@CentOS src]$ git diff The above command produces the following result − t a/src/string_operations.c b/src/string_operations.c index 8ab7f42..8fb4b00 100644 — a/src/string_operations.c +++ b/src/string_operations.c @@ -1,4 +1,14 @@ #include <stdio.h> +#include <wchar.h> + +size_t w_strlen(const wchar_t *s) + { + const wchar_t *p = s; + + while (*p) + ++p; + return (p – s); + } After testing, he commits and pushes his changes to the new branch. [jerry@CentOS src]$ git status -s M string_operations.c ?? string_operations [jerry@CentOS src]$ git add string_operations.c [jerry@CentOS src]$ git commit -m ”Added w_strlen function to return string lenght of wchar_t string” [wchar_support 64192f9] Added w_strlen function to return string lenght of wchar_t string 1 files changed, 10 insertions(+), 0 deletions(-) Note that Jerry is pushing these changes to the new branch, which is why he used the branch name wchar_support instead of master branch. [jerry@CentOS src]$ git push origin wchar_support <−−− Observer branch_name The above command will produce the following result. Counting objects: 7, done. Compressing objects: 100% (4/4), done. Writing objects: 100% (4/4), 507 bytes, done. Total 4 (delta 1), reused 0 (delta 0) To [email protected]:project.git * [new branch] wchar_support -> wchar_support After committing the changes, the new branch will appear as follows − Tom is curious about what Jerry is doing in his private branch and he checks the log from the wchar_support branch. [tom@CentOS src]$ pwd /home/tom/top_repo/project/src [tom@CentOS src]$ git log origin/wchar_support -2 The above command will produce the following result. commit 64192f91d7cc2bcdf3bf946dd33ece63b74184a3 Author: Jerry Mouse <[email protected]> Date: Wed Sep 11 16:10:06 2013 +0530 Added w_strlen function to return string lenght of wchar_t string commit 577647211ed44fe2ae479427a0668a4f12ed71a1 Author: Tom Cat <[email protected]> Date: Wed Sep 11 10:21:20 2013 +0530 Removed executable binary By viewing commit messages, Tom realizes that Jerry implemented the strlen function for wide character and he wants the same functionality in the master branch. Instead of re-implementing, he decides to take Jerry’s code by merging his branch with the master branch. [tom@CentOS project]$ git branch * master [tom@CentOS project]$ pwd /home/tom/top_repo/project [tom@CentOS project]$ git merge origin/wchar_support Updating 5776472..64192f9 Fast-forward src/string_operations.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-) After the merge operation, the master branch will appear as follows − Now, the branch wchar_support has been merged with the master branch. We can verify it by viewing the commit message or by viewing the modifications done into the string_operation.c file. [tom@CentOS project]$ cd src/ [tom@CentOS src]$ git log -1 commit 64192f91d7cc2bcdf3bf946dd33ece63b74184a3 Author: Jerry Mouse Date: Wed Sep 11 16:10:06 2013 +0530 Added w_strlen function to return string lenght of wchar_t string [tom@CentOS src]$ head -12 string_operations.c The above command will produce the following result. #include <stdio.h> #include <wchar.h> size_t w_strlen(const wchar_t *s) { const wchar_t *p = s; while (*p) ++p; return (p – s); } After testing, he pushes his code changes to the master branch. [tom@CentOS src]$ git push origin master Total 0 (delta 0), reused 0 (delta 0) To [email protected]:project.git 5776472..64192f9 master −> master Rebase Branches The Git rebase command is a branch merge command, but the difference is that it modifies the order of commits. The Git merge command tries to put the commits from other branches on top of the HEAD of

Git – Move Operation ”; Previous Next As the name suggests, the move operation moves a directory or a file from one location to another. Tom decides to move the source code into src directory. The modified directory structure will appear as follows − [tom@CentOS project]$ pwd /home/tom/project [tom@CentOS project]$ ls README string string.c [tom@CentOS project]$ mkdir src [tom@CentOS project]$ git mv string.c src/ [tom@CentOS project]$ git status -s R string.c −> src/string.c ?? string To make these changes permanent, we have to push the modified directory structure to the remote repository so that other developers can see this. [tom@CentOS project]$ git commit -m “Modified directory structure” [master 7d9ea97] Modified directory structure 1 files changed, 0 insertions(+), 0 deletions(-) rename string.c => src/string.c (100%) [tom@CentOS project]$ git push origin master Counting objects: 4, done. Compressing objects: 100% (2/2), done. Writing objects: 100% (3/3), 320 bytes, done. Total 3 (delta 0), reused 0 (delta 0) To [email protected]:project.git e86f062..7d9ea97 master −> master In Jerry’s local repository, before the pull operation, it will show the old directory structure. [jerry@CentOS project]$ pwd /home/jerry/jerry_repo/project [jerry@CentOS project]$ ls README string string.c But after the pull operation, the directory structure will get updated. Now, Jerry can see the src directory and the file present inside that directory. [jerry@CentOS project]$ git pull remote: Counting objects: 4, done. remote: Compressing objects: 100% (2/2), done. remote: Total 3 (delta 0), reused 0 (delta 0) Unpacking objects: 100% (3/3), done. From git.server.com:project e86f062..7d9ea97 master −> origin/master First, rewinding head to replay your work on top of it… Fast-forwarded master to 7d9ea97683da90bcdb87c28ec9b4f64160673c8a. [jerry@CentOS project]$ ls README src string [jerry@CentOS project]$ ls src/ string.c Print Page Previous Next Advertisements ”;

Git – Update Operation ”; Previous Next Modify Existing Function Tom performs the clone operation and finds a new file string.c. He wants to know who added this file to the repository and for what purpose, so, he executes the git log command. [tom@CentOS ~]$ git clone [email protected]:project.git The above command will produce the following result − Initialized empty Git repository in /home/tom/project/.git/ remote: Counting objects: 6, done. remote: Compressing objects: 100% (4/4), done. Receiving objects: 100% (6/6), 726 bytes, done. remote: Total 6 (delta 0), reused 0 (delta 0) The Clone operation will create a new directory inside the current working directory. He changes the directory to newly created directory and executes the git log command. [tom@CentOS ~]$ cd project/ [tom@CentOS project]$ git log The above command will produce the following result − commit d1e19d316224cddc437e3ed34ec3c931ad803958 Author: Jerry Mouse <[email protected]> Date: Wed Sep 11 08:05:26 2013 +0530 Changed return type of my_strlen to size_t commit 19ae20683fc460db7d127cf201a1429523b0e319 Author: Tom Cat <[email protected]> Date: Wed Sep 11 07:32:56 2013 +0530 Initial commit After observing the log, he realizes that the file string.c was added by Jerry to implement basic string operations. He is curious about Jerry’s code. So he opens string.c in text editor and immediately finds a bug. In my_strlen function, Jerry is not using a constant pointer. So, he decides to modify Jerry’s code. After modification, the code looks as follows − [tom@CentOS project]$ git diff The above command will produce the following result − diff –git a/string.c b/string.c index 7da2992..32489eb 100644 — a/string.c +++ b/string.c @@ -1,8 +1,8 @@ #include <stdio.h> -size_t my_strlen(char *s) +size_t my_strlen(const char *s) { – char *p = s; + const char *p = s; while (*p) ++p; } After testing, he commits his change. [tom@CentOS project]$ git status -s M string.c ?? string [tom@CentOS project]$ git add string.c [tom@CentOS project]$ git commit -m ”Changed char pointer to const char pointer” [master cea2c00] Changed char pointer to const char pointer 1 files changed, 2 insertions(+), 2 deletions(-) [tom@CentOS project]$ git log The above command will produce the following result − commit cea2c000f53ba99508c5959e3e12fff493b Author: Tom Cat <[email protected]> Date: Wed Sep 11 08:32:07 2013 +0530 Changed char pointer to const char pointer commit d1e19d316224cddc437e3ed34ec3c931ad803958 Author: Jerry Mouse <[email protected]> Date: Wed Sep 11 08:05:26 2013 +0530 Changed return type of my_strlen to size_t commit 19ae20683fc460db7d127cf201a1429523b0e319 Author: Tom Cat <[email protected]> Date: Wed Sep 11 07:32:56 2013 +0530 Initial commit Tom uses git push command to push his changes. [tom@CentOS project]$ git push origin master The above command will produce the following result − Counting objects: 5, done. Compressing objects: 100% (3/3), done. Writing objects: 100% (3/3), 336 bytes, done. Total 3 (delta 1), reused 0 (delta 0) To [email protected]:project.git d1e19d3..cea2c00 master −> master Add New Function Meanwhile, Jerry decides to implement string compare functionality. So he modifies string.c. After modification, the file looks as follows − [jerry@CentOS project]$ git diff The above command will produce the following result − index 7da2992..bc864ed 100644 — a/string.c +++ b/string.c 30Git Tutorials @@ -9,9 +9,20 @@ size_t my_strlen(char *s) return (p -s ); } +char *my_strcpy(char *t, char *s) + { + char *p = t; + + while (*t++ = *s++) + ; + + return p; + } + int main(void) { int i; + char p1[32]; char *s[] = { “Git tutorials”, “Tutorials Point” @@ -20,5 +31,7 @@ int main(void) for (i = 0; i < 2; ++i) printf(“string lenght of %s = %lun”, s[i], my_strlen(s[i])); + printf(“%sn”, my_strcpy(p1, “Hello, World !!!”)); + return 0; } } After testing, he is ready to push his change. [jerry@CentOS project]$ git status -s M string.c ?? string [jerry@CentOS project]$ git add string.c [jerry@CentOS project]$ git commit -m “Added my_strcpy function” [master e944e5a] Added my_strcpy function 1 files changed, 13 insertions(+), 0 deletions(-) Before push operation, he verifies commit by viewing log messages. [jerry@CentOS project]$ git log The above command will produce the following result − commit e944e5aab74b26e7447d3281b225309e4e59efcd Author: Jerry Mouse <[email protected]> Date: Wed Sep 11 08:41:42 2013 +0530 Added my_strcpy function commit d1e19d316224cddc437e3ed34ec3c931ad803958 Author: Jerry Mouse <[email protected]> Date: Wed Sep 11 08:05:26 2013 +0530 Changed return type of my_strlen to size_t commit 19ae20683fc460db7d127cf201a1429523b0e319 Author: Tom Cat <[email protected]> Date: Wed Sep 11 07:32:56 2013 +0530 Initial commit Jerry is happy with the changes and he wants to push his changes. [jerry@CentOS project]$ git push origin master The above command will produce the following result − To [email protected]:project.git ! [rejected] master −> master (non-fast-forward) error: failed to push some refs to ”[email protected]:project.git” To prevent you from losing history, non-fast-forward updates were rejected Merge the remote changes before pushing again. See the ”Note about fast-forwards” section of ”git push –help” for details. But Git is not allowing Jerry to push his changes. Because Git identified that remote repository and Jerry’s local repository are not in sync. Because of this, he can lose the history of the project. To avoid this mess, Git failed this operation. Now, Jerry has to first update the local repository and only thereafter, he can push his own changes. Fetch Latest Changes Jerry executes the git pull command to synchronize his local repository with the remote one. [jerry@CentOS project]$ git pull The above command will produce the following result − remote: Counting objects: 5, done. remote: Compressing objects: 100% (3/3), done. remote: Total 3 (delta 1), reused 0 (delta 0) Unpacking objects: 100% (3/3), done. From git.server.com:project d1e19d3..cea2c00 master −> origin/master First, rewinding head to replay your work on top of it… Applying: Added my_strcpy function After pull operation, Jerry checks the log messages and finds the details of Tom’s commit with commit ID cea2c000f53ba99508c5959e3e12fff493ba6f69 [jerry@CentOS project]$ git log The above command will produce the following result − commit e86f0621c2a3f68190bba633a9fe6c57c94f8e4f Author: Jerry Mouse <[email protected]> Date: Wed Sep 11 08:41:42 2013 +0530 Added my_strcpy function commit cea2c000f53ba99508c5959e3e12fff493ba6f69 Author: Tom Cat <[email protected]> Date: Wed Sep 11 08:32:07 2013 +0530 Changed char pointer to const char pointer commit d1e19d316224cddc437e3ed34ec3c931ad803958 Author: Jerry Mouse <[email protected]> Date: Wed Sep 11 08:05:26 2013 +0530

Git – Different Platforms ”; Previous Next GNU/Linux and Mac OS uses line-feed (LF), or new line as line ending character, while Windows uses line-feed and carriage-return (LFCR) combination to represent the line-ending character. To avoid unnecessary commits because of these line-ending differences, we have to configure the Git client to write the same line ending to the Git repository. For Windows system, we can configure the Git client to convert line endings to CRLF format while checking out, and convert them back to LF format during the commit operation. The following settings will do the needful. [tom@CentOS project]$ git config –global core.autocrlf true For GNU/Linux or Mac OS, we can configure the Git client to convert line endings from CRLF to LF while performing the checkout operation. [tom@CentOS project]$ git config –global core.autocrlf input Print Page Previous Next Advertisements ”;

Git – Fix Mistakes ”; Previous Next To err is human. So every VCS provides a feature to fix mistakes until a certain point. Git provides a feature that we can use to undo the modifications that have been made to the local repository. Suppose the user accidentally does some changes to his local repository and then wants to undo these changes. In such cases, the revert operation plays an important role. Revert Uncommitted Changes Let us suppose Jerry accidentally modifies a file from his local repository. But he wants to undo his modification. To handle this situation, we can use the git checkout command. We can use this command to revert the contents of a file. [jerry@CentOS src]$ pwd /home/jerry/jerry_repo/project/src [jerry@CentOS src]$ git status -s M string_operations.c [jerry@CentOS src]$ git checkout string_operations.c [jerry@CentOS src]$ git status –s Further, we can use the git checkout command to obtain a deleted file from the local repository. Let us suppose Tom deletes a file from the local repository and we want this file back. We can achieve this by using the same command. [tom@CentOS src]$ pwd /home/tom/top_repo/project/src [tom@CentOS src]$ ls -1 Makefile string_operations.c [tom@CentOS src]$ rm string_operations.c [tom@CentOS src]$ ls -1 Makefile [tom@CentOS src]$ git status -s D string_operations.c Git is showing the letter D before the filename. This indicates that the file has been deleted from the local repository. [tom@CentOS src]$ git checkout string_operations.c [tom@CentOS src]$ ls -1 Makefile string_operations.c [tom@CentOS src]$ git status -s Note − We can perform all these operations before commit. Remove Changes from Staging Area We have seen that when we perform an add operation, the files move from the local repository to the stating area. If a user accidently modifies a file and adds it into the staging area, he can revert his changes, by using the git checkout command. In Git, there is one HEAD pointer that always points to the latest commit. If you want to undo a change from the staged area, then you can use the git checkout command, but with the checkout command, you have to provide an additional parameter, i.e., the HEAD pointer. The additional commit pointer parameter instructs the git checkout command to reset the working tree and also to remove the staged changes. Let us suppose Tom modifies a file from his local repository. If we view the status of this file, it will show that the file was modified but not added into the staging area. tom@CentOS src]$ pwd /home/tom/top_repo/project/src # Unmodified file [tom@CentOS src]$ git status -s # Modify file and view it’s status. [tom@CentOS src]$ git status -s M string_operations.c [tom@CentOS src]$ git add string_operations.c Git status shows that the file is present in the staging area, now revert it by using the git checkout command and view the status of the reverted file. [tom@CentOS src]$ git checkout HEAD — string_operations.c [tom@CentOS src]$ git status -s Move HEAD Pointer with Git Reset After doing few changes, you may decide to remove these changes. The Git reset command is used to reset or revert changes. We can perform three different types of reset operations. Below diagram shows the pictorial representation of Git reset command. Soft Each branch has a HEAD pointer, which points to the latest commit. If we use Git reset command with –soft option followed by commit ID, then it will reset the HEAD pointer only without destroying anything. .git/refs/heads/master file stores the commit ID of the HEAD pointer. We can verify it by using the git log -1 command. [jerry@CentOS project]$ cat .git/refs/heads/master 577647211ed44fe2ae479427a0668a4f12ed71a1 Now, view the latest commit ID, which will match with the above commit ID. [jerry@CentOS project]$ git log -2 The above command will produce the following result. commit 577647211ed44fe2ae479427a0668a4f12ed71a1 Author: Tom Cat <[email protected]> Date: Wed Sep 11 10:21:20 2013 +0530 Removed executable binary commit 29af9d45947dc044e33d69b9141d8d2dad37cc62 Author: Jerry Mouse <[email protected]> Date: Wed Sep 11 10:16:25 2013 +0530 Added compiled binary Let us reset the HEAD pointer. [jerry@CentOS project]$ git reset –soft HEAD~ Now, we just reset the HEAD pointer back by one position. Let us check the contents of .git/refs/heads/master file. [jerry@CentOS project]$ cat .git/refs/heads/master 29af9d45947dc044e33d69b9141d8d2dad37cc62 Commit ID from file is changed, now verify it by viewing commit messages. jerry@CentOS project]$ git log -2 The above command will produce the following result. commit 29af9d45947dc044e33d69b9141d8d2dad37cc62 Author: Jerry Mouse <[email protected]> Date: Wed Sep 11 10:16:25 2013 +0530 Added compiled binary commit 94f7b26005f856f1a1b733ad438e97a0cd509c1a Author: Jerry Mouse <[email protected]> Date: Wed Sep 11 10:08:01 2013 +0530 Added Makefile and renamed strings.c to string_operations.c mixed Git reset with –mixed option reverts those changes from the staging area that have not been committed yet. It reverts the changes from the staging area only. The actual changes made to the working copy of the file are unaffected. The default Git reset is equivalent to the git reset — mixed. hard If you use –hard option with the Git reset command, it will clear the staging area; it will reset the HEAD pointer to the latest commit of the specific commit ID and delete the local file changes too. Let us check the commit ID. [jerry@CentOS src]$ pwd /home/jerry/jerry_repo/project/src [jerry@CentOS src]$ git log -1 The above command will produce the following result. commit 577647211ed44fe2ae479427a0668a4f12ed71a1 Author: Tom Cat <[email protected]> Date: Wed Sep 11 10:21:20 2013 +0530 Removed executable binary Jerry modified a file by adding single-line comment at the start of file. [jerry@CentOS src]$ head -2 string_operations.c /* This line be removed by git reset operation */ #include <stdio.h> He verified it by using the git status command. [jerry@CentOS src]$ git status -s M string_operations.c Jerry adds the modified file to the staging area and verifies it with the git status command. [jerry@CentOS src]$ git add string_operations.c [jerry@CentOS src]$ git status The above command will produce the following result. # On branch master # Changes to be committed: # (use “git reset HEAD <file>…” to unstage) # # modified: string_operations.c # Git status is showing that the file is present in the staging area. Now,

Git – Clone Operation ”; Previous Next We have a bare repository on the Git server and Tom also pushed his first version. Now, Jerry can view his changes. The Clone operation creates an instance of the remote repository. Jerry creates a new directory in his home directory and performs the clone operation. [jerry@CentOS ~]$ mkdir jerry_repo [jerry@CentOS ~]$ cd jerry_repo/ [jerry@CentOS jerry_repo]$ git clone [email protected]:project.git The above command will produce the following result. Initialized empty Git repository in /home/jerry/jerry_repo/project/.git/ remote: Counting objects: 3, done. Receiving objects: 100% (3/3), 241 bytes, done. remote: Total 3 (delta 0), reused 0 (delta 0) Jerry changes the directory to new local repository and lists its directory contents. [jerry@CentOS jerry_repo]$ cd project/ [jerry@CentOS jerry_repo]$ ls README Print Page Previous Next Advertisements ”;

Git – Basic Concepts ”; Previous Next Version Control System Version Control System (VCS) is a software that helps software developers to work together and maintain a complete history of their work. Listed below are the functions of a VCS − Allows developers to work simultaneously. Does not allow overwriting each other’s changes. Maintains a history of every version. Following are the types of VCS − Centralized version control system (CVCS). Distributed/Decentralized version control system (DVCS). In this chapter, we will concentrate only on distributed version control system and especially on Git. Git falls under distributed version control system. Distributed Version Control System Centralized version control system (CVCS) uses a central server to store all files and enables team collaboration. But the major drawback of CVCS is its single point of failure, i.e., failure of the central server. Unfortunately, if the central server goes down for an hour, then during that hour, no one can collaborate at all. And even in a worst case, if the disk of the central server gets corrupted and proper backup has not been taken, then you will lose the entire history of the project. Here, distributed version control system (DVCS) comes into picture. DVCS clients not only check out the latest snapshot of the directory but they also fully mirror the repository. If the server goes down, then the repository from any client can be copied back to the server to restore it. Every checkout is a full backup of the repository. Git does not rely on the central server and that is why you can perform many operations when you are offline. You can commit changes, create branches, view logs, and perform other operations when you are offline. You require network connection only to publish your changes and take the latest changes. Advantages of Git Free and open source Git is released under GPL’s open source license. It is available freely over the internet. You can use Git to manage property projects without paying a single penny. As it is an open source, you can download its source code and also perform changes according to your requirements. Fast and small As most of the operations are performed locally, it gives a huge benefit in terms of speed. Git does not rely on the central server; that is why, there is no need to interact with the remote server for every operation. The core part of Git is written in C, which avoids runtime overheads associated with other high-level languages. Though Git mirrors entire repository, the size of the data on the client side is small. This illustrates the efficiency of Git at compressing and storing data on the client side. Implicit backup The chances of losing data are very rare when there are multiple copies of it. Data present on any client side mirrors the repository, hence it can be used in the event of a crash or disk corruption. Security Git uses a common cryptographic hash function called secure hash function (SHA1), to name and identify objects within its database. Every file and commit is check-summed and retrieved by its checksum at the time of checkout. It implies that, it is impossible to change file, date, and commit message and any other data from the Git database without knowing Git. No need of powerful hardware In case of CVCS, the central server needs to be powerful enough to serve requests of the entire team. For smaller teams, it is not an issue, but as the team size grows, the hardware limitations of the server can be a performance bottleneck. In case of DVCS, developers don’t interact with the server unless they need to push or pull changes. All the heavy lifting happens on the client side, so the server hardware can be very simple indeed. Easier branching CVCS uses cheap copy mechanism, If we create a new branch, it will copy all the codes to the new branch, so it is time-consuming and not efficient. Also, deletion and merging of branches in CVCS is complicated and time-consuming. But branch management with Git is very simple. It takes only a few seconds to create, delete, and merge branches. DVCS Terminologies Local Repository Every VCS tool provides a private workplace as a working copy. Developers make changes in their private workplace and after commit, these changes become a part of the repository. Git takes it one step further by providing them a private copy of the whole repository. Users can perform many operations with this repository such as add file, remove file, rename file, move file, commit changes, and many more. Working Directory and Staging Area or Index The working directory is the place where files are checked out. In other CVCS, developers generally make modifications and commit their changes directly to the repository. But Git uses a different strategy. Git doesn’t track each and every modified file. Whenever you do commit an operation, Git looks for the files present in the staging area. Only those files present in the staging area are considered for commit and not all the modified files. Let us see the basic workflow of Git. Step 1 − You modify a file from the working directory. Step 2 − You add these files to the staging area. Step 3 − You perform commit operation that moves the files from the staging area. After push operation, it stores the changes permanently to the Git repository. Suppose you modified two files, namely “sort.c” and “search.c” and you want two different commits for each operation. You can add one file in the staging area and do commit. After the first commit, repeat the same procedure for another file. # First commit [bash]$ git add sort.c # adds file to the staging area [bash]$ git commit –m “Added sort operation” # Second commit [bash]$ git add search.c # adds file to the staging area [bash]$ git commit –m “Added search operation” Blobs Blob stands for Binary Large Object. Each

Git – Life Cycle ”; Previous Next In this chapter, we will discuss the life cycle of Git. In later chapters, we will cover the Git commands for each operation. General workflow is as follows − You clone the Git repository as a working copy. You modify the working copy by adding/editing files. If necessary, you also update the working copy by taking other developer”s changes. You review the changes before commit. You commit changes. If everything is fine, then you push the changes to the repository. After committing, if you realize something is wrong, then you correct the last commit and push the changes to the repository. Shown below is the pictorial representation of the work-flow. Print Page Previous Next Advertisements ”;