Git and Github. Simple recipes
When developing your own project, sooner or later, you have to think about where to store the source code and how to support work with several versions. In the case of work for a company, this is usually solved for you and you only need to maintain the accepted rules. There are several commonly used version control systems, and we’ll look at one of the most popular ones - Git and the Github service.
Git appeared as a source control tool in the Linux operating system and won many fans in the Open Source environment.
The Github service provides hosting (storage) of source texts both on a paid and free basis. This is one of the largest systems that users love Open Source. The main difference of the paid version is the ability to create private repositories (repositories) of the source code, and if you have nothing to hide, you can safely use the free version.
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After you have started work on the project and wrote some working prototype, you will have a desire to save the results of the work. This can also be useful if you want to continue working on another computer. The simplest solution is to save everything on a flash drive. This option works well, but if there is an internet connection (and now anyone has one), then it is convenient to use Git / Github systems.
This article will describe basic scenarios for using Git / Github systems when working on a project in Linux using the command line. All examples were tested on a Linux system with Ubuntu 14.04 and Git 1.9.1. If you use another distribution, there may be differences.
Suppose your project is in the / home / user / project folder. Before you save the source, you can see if there are temporary files in the project folder and, if possible, delete them.
To view the folder, it is convenient to use the tree command, which shows not only the contents of each folder, but also a tree structure of directories.
Often, temporary files contain specific suffixes by which they are easy to detect and subsequently delete. To find such files you can use the find command . As an example, let's see how to find all the files that are generated by the Python compiler and have the extension .pyc
Go to the folder with the project / home / user / project :
And show the list of files with the extension .pyc :
This command will list all files with the .pyc extension in the current directory and its subdirectories. To delete the found files, just add the -delete switch to this command:
It is highly recommended not to rush and not to add this key right away. The first time to call the command to view the files and just making sure that nothing useful to add the delete key has appeared in the list.
Create a local repository in the project folder:
After executing this command, a new folder will appear with the name .git . It will contain several files and subdirectories. At the moment, the version control system still does not see our files.
To add files, use the command:
After executing the command, the readme file will be added to the version control system (of course, if it was already in that project). When a file is added, a hash value is generated, which looks like this:
The added files are stored in the .git / objects / xx / yyyyyyyy folder , with the first 2 digits of the hash used to specify the directory, and the rest of the hash value is the file name. Our added file will be located here:
What is easy to see with the command:
The file itself is an archive that is easy to unpack and display, indicating the full value of the hash.
In order to add all files from the current directory, enter:
If you need to add files from the current directory and from all subdirectories, use:
To prevent temporary files from entering the system, you can add them to a .gitignore file, which you need to create yourself and place in the root directory of the project (on the same level as the .git directory).
For example, if you add the following line in the .gitignore file to * .pyc , then all files with the .pyc extension will not be added to the repository.
After adding files, all changes are in the so-called staging (or cached ) area . This is some temporary storage that is used to accumulate changes and from which the actual versions of projects are created ( commit ).
To view the current status, you can use the command:
After executing the command, we will see that the stage area contains our file:
If you continue to make changes to the readme file , then after calling the git status command, you will see two versions of the file.
To add new changes, just repeat the command. The git add command not only adds new files, but also all changes to files that were added earlier.
You can cancel adding the readme file to the staging area with the command:
After executing the command, the readme file will be marked as unmodified by the system.
After we have added the necessary files to the staging area, we can create a project version. Using the command:
Each new version is accompanied by a comment.
After the commit, we will be able to find two new objects inside the .git repository.
Let's see what's inside:
The -t switch indicates the type of object. As a result, we see:
For the second object:
Result:
For the very first file:
We see:
If we continue to examine the contents of these files, we will find a tree structure. From each commit, you can follow the links through all the modified files. For practical use, this is not very necessary, but it may be easier to understand what happens when working with the Git system.
The very first version can not be canceled. It can only be fixed. If you want to add changes to the latest version, then after you execute the commit command, add the necessary changes and call:
Or so:
The key - no-edit is needed in order not to re-enter the comment.
You can view the changes you made with the latest commit:
Or so:
The key --name-only is needed to show only the names of the changed files. Without it, a list of all changes will be displayed for each changed file.
If you continued to work and changed only those files that have already been added to the system with the git add command, you can commit with one command:
To view a list of all commits, use the command:
Or so:
The --oneline key is needed to reduce the amount of information displayed on the screen. With this key, each commit is shown in one line. For example:
In order to view the changes for a particular commit, it is enough to add a hash value to the git show command, which can be obtained using the previous command.
To cancel the last commit (except the first one), you can use the following command:
In order to delete all files in the folder that do not belong to the project and are not saved in the repository, you can use the command:
Until now we have been working with a local repository, which was saved in a folder on the computer. If we want to be able to save the project on the Internet, create a repository on Github. First you need to register on github.com under the name myuser (in your case it could be any other name).
After registration, press the "+" button and enter the name of the repository. Select the type of Public (the repository is always Public for the free version) and click Create .
As a result, we created a repository on Github. On the screen we will see instructions on how to connect our local repository with the newly created one. Some teams are already familiar to us.
Add a remote repository (via SSH) under the name origin (instead of origin, you can use any other name).
We can view the result of adding with the command:
If everything was done correctly, we will see:
To unregister a remote repository, enter:
This may be necessary if you want to change SSH access to HTTPS . Then you can add it again, for example, under the name github and the HTTPS protocol .
The next command will put all the changes that were made in the local repository on Github.
The -u switch is used to establish a connection between the remote github repository and your master branch. You can transfer all further changes to a remote repository with a simplified command.
Once the repository has been created on Github, you can copy it to any other computer. To do this, use the command:
The result of this command is the creation of the project folder in the current directory. This folder will also contain a local repository (that is, a .git folder).
You can also add the name of the folder in which you want to place the local repository.
Several developers or you yourself can work with one repository from different computers, for example, if you are working on the same project at home and at work.
To receive updates from a remote repository, use the command:
If you change your local files, the git pull command will generate an error. If you are sure that you want to overwrite local files with files from a remote repository, then run the following commands:
Replace github with the name of your remote repository you registered with git push -u .
As we already know, in order to put the changes on the remote repository, use the command:
If the remote repository contains files with a newer version than you have in the local one, then the git push command will generate an error. If you are sure that you want to overwrite files in the remote repository despite the version conflict, use the command:
Sometimes it becomes necessary to postpone your current changes and work on files that are in the remote repository. To do this, postpone the current changes with the command:
After executing this command, your local directory will contain the same files as for the last commit. You can download new files from a remote repository with the git pull command and then return your changes that you postponed with the command:
We looked at the basic scenarios for working with Git and Github systems. Each command above has significantly more keys and, accordingly, capabilities. A gradual study of them will give you the opportunity to easily guard your sources and concentrate more directly on the development.
Git appeared as a source control tool in the Linux operating system and won many fans in the Open Source environment.
The Github service provides hosting (storage) of source texts both on a paid and free basis. This is one of the largest systems that users love Open Source. The main difference of the paid version is the ability to create private repositories (repositories) of the source code, and if you have nothing to hide, you can safely use the free version.
')
After you have started work on the project and wrote some working prototype, you will have a desire to save the results of the work. This can also be useful if you want to continue working on another computer. The simplest solution is to save everything on a flash drive. This option works well, but if there is an internet connection (and now anyone has one), then it is convenient to use Git / Github systems.
This article will describe basic scenarios for using Git / Github systems when working on a project in Linux using the command line. All examples were tested on a Linux system with Ubuntu 14.04 and Git 1.9.1. If you use another distribution, there may be differences.
Creating a local repository
Suppose your project is in the / home / user / project folder. Before you save the source, you can see if there are temporary files in the project folder and, if possible, delete them.
To view the folder, it is convenient to use the tree command, which shows not only the contents of each folder, but also a tree structure of directories.
Often, temporary files contain specific suffixes by which they are easy to detect and subsequently delete. To find such files you can use the find command . As an example, let's see how to find all the files that are generated by the Python compiler and have the extension .pyc
Go to the folder with the project / home / user / project :
cd /home/user/project And show the list of files with the extension .pyc :
find . -name *.pyc This command will list all files with the .pyc extension in the current directory and its subdirectories. To delete the found files, just add the -delete switch to this command:
find . -name *.pyc -delete It is highly recommended not to rush and not to add this key right away. The first time to call the command to view the files and just making sure that nothing useful to add the delete key has appeared in the list.
Create a local repository in the project folder:
git init After executing this command, a new folder will appear with the name .git . It will contain several files and subdirectories. At the moment, the version control system still does not see our files.
Add files to local repository
To add files, use the command:
git add readme After executing the command, the readme file will be added to the version control system (of course, if it was already in that project). When a file is added, a hash value is generated, which looks like this:
9f2422325cef705b7682418d05a538d891bad5c8 The added files are stored in the .git / objects / xx / yyyyyyyy folder , with the first 2 digits of the hash used to specify the directory, and the rest of the hash value is the file name. Our added file will be located here:
.git/objects/9f/2422325cef705b7682418d05a538d891bad5c8 What is easy to see with the command:
ls .git/objects The file itself is an archive that is easy to unpack and display, indicating the full value of the hash.
git cat-file -p 9f2422325cef705b7682418d05a538d891bad5c8 In order to add all files from the current directory, enter:
git add . If you need to add files from the current directory and from all subdirectories, use:
git add --all To prevent temporary files from entering the system, you can add them to a .gitignore file, which you need to create yourself and place in the root directory of the project (on the same level as the .git directory).
For example, if you add the following line in the .gitignore file to * .pyc , then all files with the .pyc extension will not be added to the repository.
After adding files, all changes are in the so-called staging (or cached ) area . This is some temporary storage that is used to accumulate changes and from which the actual versions of projects are created ( commit ).
To view the current status, you can use the command:
git status After executing the command, we will see that the stage area contains our file:
new file: readme If you continue to make changes to the readme file , then after calling the git status command, you will see two versions of the file.
new file: readme modified: readme To add new changes, just repeat the command. The git add command not only adds new files, but also all changes to files that were added earlier.
git add readme You can cancel adding the readme file to the staging area with the command:
git rm --cached readme After executing the command, the readme file will be marked as unmodified by the system.
Creating a project version
After we have added the necessary files to the staging area, we can create a project version. Using the command:
git commit -m "comment" Each new version is accompanied by a comment.
After the commit, we will be able to find two new objects inside the .git repository.
.git/objects/9f/2422325cef705b7682418d05a538d891bad5c8 .git/objects/65/7ab4c07bd3914c7d66e4cb48fe57f5c3aa7026 .git/objects/da/c6721c3b75fcb3c9d87b18ba4cef2e15e0a3d3 Let's see what's inside:
git cat-file -t 657ab4c07bd3914c7d66e4cb48fe57f5c3aa7026 The -t switch indicates the type of object. As a result, we see:
commit For the second object:
git cat-file -t dac6721c3b75fcb3c9d87b18ba4cef2e15e0a3d3 Result:
tree For the very first file:
git cat-file -t 9f2422325cef705b7682418d05a538d891bad5c8 We see:
blob If we continue to examine the contents of these files, we will find a tree structure. From each commit, you can follow the links through all the modified files. For practical use, this is not very necessary, but it may be easier to understand what happens when working with the Git system.
The very first version can not be canceled. It can only be fixed. If you want to add changes to the latest version, then after you execute the commit command, add the necessary changes and call:
git commit -m "comment" --amend Or so:
git commit --amend --no-edit The key - no-edit is needed in order not to re-enter the comment.
You can view the changes you made with the latest commit:
git show Or so:
git show --name-only The key --name-only is needed to show only the names of the changed files. Without it, a list of all changes will be displayed for each changed file.
If you continued to work and changed only those files that have already been added to the system with the git add command, you can commit with one command:
git commit -a -m "comment" To view a list of all commits, use the command:
git log Or so:
git log --oneline The --oneline key is needed to reduce the amount of information displayed on the screen. With this key, each commit is shown in one line. For example:
2b82e80 update 657ab4c first In order to view the changes for a particular commit, it is enough to add a hash value to the git show command, which can be obtained using the previous command.
git show 657ab4c To cancel the last commit (except the first one), you can use the following command:
git reset HEAD~1 In order to delete all files in the folder that do not belong to the project and are not saved in the repository, you can use the command:
git clean -df Creating a repository on Github
Until now we have been working with a local repository, which was saved in a folder on the computer. If we want to be able to save the project on the Internet, create a repository on Github. First you need to register on github.com under the name myuser (in your case it could be any other name).
After registration, press the "+" button and enter the name of the repository. Select the type of Public (the repository is always Public for the free version) and click Create .
As a result, we created a repository on Github. On the screen we will see instructions on how to connect our local repository with the newly created one. Some teams are already familiar to us.
Add a remote repository (via SSH) under the name origin (instead of origin, you can use any other name).
git remote add origin git@github.com:myuser/project.git We can view the result of adding with the command:
git remote -v If everything was done correctly, we will see:
origin git@github.com:myuser/project.git (fetch) origin git@github.com:myuser/project.git (push) To unregister a remote repository, enter:
git remote rm origin This may be necessary if you want to change SSH access to HTTPS . Then you can add it again, for example, under the name github and the HTTPS protocol .
git remote add github https://github.com/myuser/project.git The next command will put all the changes that were made in the local repository on Github.
git push -u github master The -u switch is used to establish a connection between the remote github repository and your master branch. You can transfer all further changes to a remote repository with a simplified command.
git push Transferring the repository to another computer
Once the repository has been created on Github, you can copy it to any other computer. To do this, use the command:
git clone https://github.com/myuser/project.git The result of this command is the creation of the project folder in the current directory. This folder will also contain a local repository (that is, a .git folder).
You can also add the name of the folder in which you want to place the local repository.
git clone https://github.com/myuser/project.git <myfolder> Work with one repository from different computers
Several developers or you yourself can work with one repository from different computers, for example, if you are working on the same project at home and at work.
To receive updates from a remote repository, use the command:
git pull If you change your local files, the git pull command will generate an error. If you are sure that you want to overwrite local files with files from a remote repository, then run the following commands:
git fetch --all git reset --hard github/master Replace github with the name of your remote repository you registered with git push -u .
As we already know, in order to put the changes on the remote repository, use the command:
git push If the remote repository contains files with a newer version than you have in the local one, then the git push command will generate an error. If you are sure that you want to overwrite files in the remote repository despite the version conflict, use the command:
git push -f Sometimes it becomes necessary to postpone your current changes and work on files that are in the remote repository. To do this, postpone the current changes with the command:
git stash After executing this command, your local directory will contain the same files as for the last commit. You can download new files from a remote repository with the git pull command and then return your changes that you postponed with the command:
git stash pop Conclusion
We looked at the basic scenarios for working with Git and Github systems. Each command above has significantly more keys and, accordingly, capabilities. A gradual study of them will give you the opportunity to easily guard your sources and concentrate more directly on the development.
Source: https://habr.com/ru/post/273897/
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