GIT

 This article is in a final form but it needs to be reviewed.  GIT -> DEFINITION -> open source distributed version control system -> its main purpose is to track changes to files and directories in a project -> it is, however, a very powerful tool which provides features such as -> versioning, branching, forking and navigating between all of these -> allows multiple people to easily work on the same project without interference -> limited debugging -> easy repository integration -> enforcing a working flow -> much more :)								   -> it is used mostly in software development environments, to track changes to source code.   -> CONCEPT -> low level storage of data-> at its core, Git can be thought of as a table of -> KEYS -> the SHA1 hash of a VALUE it references												      -> a hash is a string which represents the content of an object, not the object itself    						     					      -> VALUES -> any sequence of bytes (file contents, directories etc)						     							-> the values are stored under these KEYS (are referenced by the keys)													-> each VALUE represens an OBJECT -> an object is a sequence of bytes, which is, a VALUE									  								  -> each object is referenced by a KEY, which is, a SHA1 hash								  									  -> if two objects are identical, Git will store only one and will use it everywhere it is referenced							          									  -> a file and its content is stored -> the content in a (is a) BLOB object and is the actual hashed value which gives the KEY -> the filename and permissions in the TREE object -> for example, if two files have the exact same content, the TREES where these files are, will reference the same BLOB (and not two identical blobs) -> three main types of objects -> BLOB -> it is the contents of a file, at some point in time, stored in Git -> it is the actual data -> TREE -> a directory stored in Git -> it has a list of hashes for each object it contains -> it contains filenames which point to blobs and another trees -> COMMITS -> is just a piece of text and nothing else -> Just git cat-file on the SHA of a commit -> points to a graph of trees and blobs that represent the project at the moment of that commit -> contains -> the commit metadata -> the hash of the parent commit -> It is missing if first commit -> this means that a commit also points to its parent commit, which is the previous commit where this 'current' commit originated from. -> the hash of the content of the root directory (tree) of the project -> TAGS -> are used as another way to reference a commit beside its hash -> two types -> SIMPLE TAG -> it is a pointer to the commit where it was created -> a reference to a commit, just like a branch -> it is a simple name, and nothing else. -> ANNOTATED TAG -> just like the simple tag, is a pointer to the commit where it was created -> it is the fourth type of object in Git -> it is made of two parts -> a pointer to the hash of a BLOB -> the BLOB which contains tag metadata and another hash, of the actual commit tagged -> works by moving data around four conceptual areas -> WORKING AREA -> the place where you keep the files and folders you are currently working on							 	                   -> it is the directory where you do the actual work (edits) -> INDEX-> the changes are moved here before a commit -> it is the area where changes from working directory are staged before commiting -> it specifically is the 'index' file in the .git repository -> while in its implementation it is supposed to be seen as a temporary transition area, index actually contains all the data, just like the repository -> the message 'nothing to commit, working tree clean' means that the index area contains the same files as the repository -> REPOSITORY -> contains all the history of the project -> commited changes go here -> stored in the .git folder -> structure -> .gitignore -> specifies which files from the project are ignored by Git -> accepts regex patterns -> "ignores" means that git will never display the files as untracked or staged, and it won't track any changes to them -> .git\objects -> folder where Git stores all its objects. -> sort of an objects database -> first two hexa chars from the object's SHA1 hash will be the name of the subdirectory where the object is stored -> the rest of the hexa chars from the object's SHA1 hash will be the name of the file where the object is stored -> .git\info\attributes -> textfile which contains configuration settings (called attributes) regarding files or groups of files within a repository -> attributes can also be located in .gitattributes file -> attributes dictate how the files are handled -> for example -> manually specify what files are binary or not -> specify what diff tool to use for specific files or types of files -> what files are removed from an export of the repository -> in .gitattributes -> tests export-ignore -> smudge and clean filters -> are 2 functions which are applied to files when they are moved between working directory and index -> used mainly to replace sensitive information with placeholders -> Clean is called when files are staged (moved to INDEX) -> Smudge is called when files are moved back into WORKING DIRECTORY -> for example -> two filters are configured -> smudge -> git config --local filter.updateAPIKey.smudge 'sed "s/{SECURE_API_KEY}/a1693afecca123"' -> clean -> git config --local filter.updateAPIKey.clean 'sed "s/a1693afecca123/{SECURE_API_KEY}"' -> in .gitattributes -> *.js filter=updateAPIKey -> in this example -> in .gitattributes has been specified that the updateAPIKey filter will be used on all .js files -> when .js files are moved from WORKING DIRECTORY to INDEX, updateAPIKey.clean function will be applied to them, which is 'sed....' -> when .js files are moved from the INDEX to the WORKING DIRECTORY, updateAPIKey.smudge function will be applied to them -> .git\hooks -> HOOKS -> scripts executed in response to a specific action which occurred in a repository -> the script itself is basically an executable file (bash script) -> used to implement workflows -> two types -> client-side hooks -> scripts that execute on the client machine -> areas of implementation -> pre-commit -> after the git commit command is issued, but before the commit message is generated -> prepare-commit-msg -> the commit message is generated and it can be customized -> commit-msg -> the user finished customizing the commit message -> post-commit -> the commit has been completed -> usually used for notifications -> used to -> improve workflows for those using the repository -> cannot enforce policies (since the repo is local, those hooks enforcing policies can just be removed) -> usually to run pre-commit checks against the code -> use cases -> running tests -> check the modifications against best practices -> prepare commit message templates -> linting files -> cleaning up files -> post commit notification for some kind of notification/logging system. -> implementation points -> the hooks sample files are located within .git/hooks -> git hooks files must be executable -> git hooks scripts must be written to always exit with a non 0 status code if any of the script's actions fail -> otherwise, the commit process continues, even if the actions in the hook failed. -> status codes are the communication method between Git and it hooks. -> git config --local core.hooksPath  -> specifies a different directory location to store Git hooks -> this allows pushing the client hooks as .git folder is not pushed. -> if this config is made, the hooks will next be called from  -> server-side hooks -> scripts that execute on the Git server -> areas of implementation -> pre-receive -> receives any of the refs updated -> used to examine the incoming push and may take action per push -> update -> called per ref -> examines each ref and may take actions per ref -> post-receive -> called after a successful push -> used to -> enforce policies (those working on the repo do not have access to the Git server receiving the push) -> for notifications -> use cases -> enforce a commit message format -> enforce user identity info -> enforce the signing of tags/commits -> blocking access for specific IP addresses -> blocking specific file extensions -> .git\refs\ -> a folder where Git stores the files which contains references (like branches, tags, remotes) -> references are found all over Git, not only in this folder. For instance, each commit object references its parent. -> Git uses references between commits to track history and references from commits to trees and blobs to track content (the state of the project) -> HEAD -> is a reference that points -> usually to a branch ref, in which case HEAD points indirectly to a commit. -> rarely, directly to a commit (contains a hash) -> this is also called the 'detached HEAD' state. -> a detached HEAD is a commit which doesn't belong to any branch -> its purpose is to -> reflect the current commit. The commit that HEAD points to (either directly via hash or indirectly via a branch ref), is the current one. -> determine the parent of the next commit. The command git commit, creates a new commit object, whose parent is the commit which HEAD points to. -> tell you where you are. Since it points to the current commit, it is a good indicator to where in the project's history you are working. -> referencing commits relatively to HEAD, in shell -> HEAD ^ -> parent commit of head -> HEAD ^^ -> parent of parent of HEAD -> HEAD~2 -> HEAD then back two commits -> HEAD ^2 -> the second parent of HEAD (if HEAD is a merge commit) -> HEAD@{'1 month ago'} -> for instance -> git show HEAD~2 -> .git\refs\heads -> contains the branch references -> BRANCH -> is -> a pointer to a commit (directly, via SHA1 hash)							| while the 'branch' term refers to the actual reference, the series of -> a series of commits, where each commit is linked to the previous one in a parent-child relationship. | commits that this reference points to is also called a 'branch' -> the branch ref points to the last (latest) commit in the series. -> BRANCHING -> a newly initialized repo has a single branch, called master or main. -> when a commit is made -> a new commit object is created which points at its parent -> the branch ref is moved along to point at the new commit, which implicitly moves HEAD to point at the new commit, which means that this new commit will be the parent of the next. -> this is how a series of linked commits (a branch) is created. -> if a new branch is created -> a new branch ref is created. -> the new branch ref points at the current commit -> at this point, the current commit has two branch refs pointing at it, the old branch, and the newly created one. -> the branch ref that HEAD points to (as example, the new branch ref) will be moved along at the next commit, and the next, and so on, creating a series of linked commits. -> switching to the old branch -> moves HEAD to point to the old branch ref -> commiting will move the old branch ref along with the new commits, creating another series of linked commits. -> at this point we have two separate series of linked commits, both of which share a common commit -> called the Ancestor Commit -> switching to a branch -> since HEAD points to the branch ref, the commit that the branch ref points to, is the current commit. -> switching the branch, makes HEAD point to another branch ref which, in turn, points to another commit. -> switching HEAD to another commit updates the INDEX and the WORKING AREA with the state described by the commit (see git checkout command). -> as each commit points to its parent, switching to a branch ref switches to a series of linked commits. Effectively, switches to a branch. -> .git\refs\tags -> contains the tags -> .git\refs\remotes -> contains subfolders for each remote, each containing the branches of that remote -> .git\config -> git config file -> .git\index -> a binary file -> contains a list of all files in the current branch,their checksums, timestamps and filenames -> it can be seen as as the file that stores what we need to commit. -> it is the same as the INDEX that we are talking about throughout this document -> STASH -> contains the stashed changes from index and working directory that is not yet commited -> can be though of as an area where the work can be saved for later, if somethin else needs to be done -> its content cannot be modified, other than using git stash directly. -> can contain multiple elements -> one element represents the all the changes stashed once -> each element has a serial ID and a commit hash to make it easier to identify -> for example -> a regular flow of data across the four areas when working with Git would look like: -> same version of files in WORKING AREA, INDEX and REPOSITORY -> modifications -> GIT ADD -> modifications added to the INDEX -> GIT COMMIT -> creates a new snapshot/version of the INDEX -> in depth explanation -> cloning a repository, or initiating one, would result in the same version of all files in WORKING DIRECTORY, INDEX and REPOSITORY -> it starts with a commited version of the index -> this is the version present in the repository -> working directory and the index have the same versions of the files -> changes are made to files (the version in the working directory) -> the changes are not permanent, they can be undone -> displayed with red text by "git status" -> changes that are final and deemed good are added to the tree (staged/added to the staging area) -> displayed with green text by git status -> changes still not permanent -> adding files to the staging area can be seen as preparing a "final" version of the index -> if the index is what we want, a commit is made -> that version of the index is made final with a commit (we are sure that's how we want the index to be) -> the changes are permanent "for now" representing a new version of the repository -> it is also called a snapshot -> this "final for now" version has been saved and we can revert to it																							    -> the local repository is updated with this version -> else, changes are reverted/deleted and we'll work towards a better result -> no need to use the Stashing functionality yet. -> COMMANDS -> most of the commands can be understood logically by asnwering TWO QUESTIONS -> how does this command move information across the four conceptual areas described above? -> how does this command change the Repository? -> NOTE -> the commands below and their functions are described, first, from a conceptual point of view (what it is supposed to do in Git). -> However, the -2Q> describes their actual actions from the perspective of the two questions, for a better understanding (I hope) -> paths (pathspecs) -> a path is just a way to specify files or directories to be targeted by a command. -> for example -> git add myfile.txt -> myfile.txt is basically a path that identifies myfile.txt within the WORKING DIRECTORY. -> git add mydir/ -> mydir/ is a path that identifies mydir/ within the WORKING DIRECTORY -> throughout this document, a ['file'] in the syntax of a command refers to a path. -> so basically, in the context of Git, a path is understood as a file, multiple files, directory or multiple directories -> most Git commands can be executed on paths -> for example -> git reset HEAD file.ext -> unstages the staged file file.ext only. -> git reset --hard HEAD file.ext -> --hard is incompatible with paths. Throws an error -> git checkout HEAD file.txt -> GIT INIT -> starts tracking the changes in a folder by initializing a new git repository. -> effectively creates a new git project (called a repository) -> creates the .git HIDDEN FOLDER -> contains all the necessary tools to track the project -> contains the whole repository -> this is the folder copied from a remote source when cloning -> OPTIONS -> --bare -> initializes a bare repository -> a repository without a WORKING DIRECTORY -> it is the repo as stored on a server -> it can be pulled from and pushed to, but cannot be edited directly. -> no remotes are configured for the repo -> GIT CLONE ['uri'] -> clones a remote repository -> when cloning, only the main branch is copied (everything it has, including the log), and it is set to track the main (master) branch of the remote repo -> the other branches will be copied locally afterwards, if wished so		                     -> when a repo is cloned, Git automatically adds a remote relationship with the original remote repo, called "origin" -> OPTIONS -> --bare -> clones the repository in its bare state (without the WORKING DIRECTORY) -> it is the repo as stored on a server -> it can be pulled from and pushed to, but cannot be edited directly. -> no remotes are configured for the repo -> GIT ADD ['file'] -> adds the files (untracked) or modifications (tracked), from the WORKING AREA, to the INDEX -> when a commit is made, the current form of the INDEX is saved (snapshot) and the local REPOSITORY is updated -> also known as the STAGING AREA -2Q> copies the updated file(s) from the WORKING DIRECTORY, to the INDEX, overwriting the previous ones (if applicable). -> OPTIONS -> -n / --dry-run -> do not perform the ADD operation, just show what files would be ADDED -> -v -> verbose -> -u -> stages all updated files, but not untracked files -> -A -> stages all files including both untracked files and updated files -> --patch -> allows the staging of only parts of a file (called hunks) -> the result of add --patch shown in git status will be the same file in both staged and unstaged areas -> GIT COMMIT -> commits the changes from the INDEX, to the REPOSITORY -> each commit creates a new snapshot (version) of the repository -2Q> copies the files from the index to the repository -2Q> creates a new commit object in the database -2Q> creates another objects -2Q> updates the current branch (moved the pointer) -> OPTIONS -> -a -> automatically stages all modifications, effectively skipping the staging area step -> -m "message" -> adds a message to the commit, without opening the editor -> if -m is not used, Git commit opens the default editor so a commit message can be wrote. After this, it will commit to the staged modifications. -> --author -> allows to specify an author for this commit, different from the configured one. -> --amend -> allows amending the latest commit (making changes to it) -> it is useful only for the latest commit -2Q> Git copies the commit that is being amended, add the amends to the copy (like making a new commit - regular process) and moves HEAD to it. -> since it no longer has a branch, the commit that was amended will be garbage collected -> --amend --author [User Name ] -> allows changing the author of the last commit -> it is a shortcut to the --amend process. -> GIT CLEAN -> cleans the working directory -> OPTIONS -> -n -> shows what would happen if the command is issued, without making any modifications -> -f -> performs the clean -> GIT STATUS -> shows the modifications from the working tree (working directory), not yet commited to the repository (modifications to the tracked files, or adding new, untracked files) -> shows only for the current branch -> shows if in detached HEAD state -> shows if the current branch is in sync with the ORIGIN repo branch -> OPTIONS -> -s / --short -> shows a shortened version of output -> "M" (modified) is a modified file, which may be staged or not. "??" (unknown) is an unstaged untracked file. "A" (added) is a staged untracked file -> GIT LOG -> shows the history of the repository on current branch -> the first commits displayed are the latest (reverse chronological order) -> OPTIONS -> -1 -> any number -> limits the number of commits displayed -> --oneline -> shows the commits in a one line shortened version -> displays the first digits of the SHA-1 hash, refs and commit message -> --stat -> shows more details about the modifications in each commit -> --patch -> shows the full diff for each commit -> --all -> shows for all branches -> --decorate -> shows tags and any other notations -> --graph -> provides a graph of repository's evolution. Displays the log in a graph. -> when --graph is used, most commonly the following options are also used for better formatting: --all, --decorate, --oneline -> Example: git log --graph --all --decorate --oneline -> --grep string -> filters the commits. Shows only those who contain the 'string' -> -Gstring -> filters the commits. Shows only those who either added or removed the 'string'. -> .. -> finds all the commits in branch2 which are not in branch1 -> GIT REFLOG -> displays the reference log -> a log of all the actions that affected a reference such as -> new commits (branch reference moves onwards) -> branch checkout (HEAD reference updates) -> rebasing -> etc.			      				     -> is a good way to recover commits that have been lost, until they are garbage collected (as in the process of a rebase where the original commits no longer have a reference branch associated to them) -> is strictly local information (cloning the repo results in creating a new reflog) -> the commit hash that is in the reflog is the commit that the reference was pointing to when the action took place. -> GIT SHORTLOG -> provides a summarized version of the logs "suitable for release announcements" -> with no options, basically lists the authors and their commits on a branch -> OPTIONS -> -s -> summarizes the output by showing only the authors and the number of commits -> -n -> sorts the output based on the number of commits per author -> -e -> shows the author's email -> GIT SHOW [object] -> shows information regarding the object (commit, blob, tree, etc) -> git show -> is a combination of git log and git diff -> GIT BLAME [path] -> shows each line in the file and the commit that the line originates from, the user and the date of the commit -> GIT STASH -> stashes the working directory and staging area as WIP and clears the working directory -2Q> two actions -> copies all the changes from WORKING AREA and INDEX that are not yet commited, in the STASH area -> checksout the current commit (clearing the INDEX and the WORKING AREA) -> OPTIONS -> save -> the default option -> git stash = git stash save -> list -> lists the contents of the stash -> show -> shows a more detailed view of what files have been stashed -> pop -> returns the stashed changes in the working directory/index and removes them from stash -> apply [element] -> reapplies the stashed changes of the element supplied, to the working directory/index while also keeping them in stash -> if no element is supplied, applies the most recently stashed changes -> an element is a set of changes from the WORKING AREA and INDEX, stashed once using git stash save. -> drop -> removes the last stashed changes -> clear -> clears the stash -> branch [branchname] -> creates a new branch and applies the stashed changes to it					 -> --include-untracked -> stashes untracked files -> --patch -> executes git stash on a part of the file only (called hunk) -> GIT DIFF -> with no arguments or options, shows the differences between the WORKING AREA and the INDEX -> [commit] -> with one argument, shows the differences between the specified commit and the current working directory -> the commit is specified either by its SHA hash or using HEAD -> HEAD = last commit -> HEAD~1 = one commit back (1 = number of commits back) -> [commit] [commit] -> shows the differences between two commits -> [commit][commit][file] would list the differences related to the supplied file between the supplied commits -> [commitA]...[commitB] -> shows the differences between the common-ancestor-commit of commitA and commitB and commitB -> useful in the context of branches -> it is useful to display the differences between the master as it was when the feature was created, and feature as it is now -> it is equivalent to $git diff ($git merge-base [commitA][commitB]) commitB -> the difference between git diff and three-dots-git-diff is -> git diff -> shows all the differences between branches 3-dots-git-diff -> shows just the differences between the common-ancestor of the two branches (master and feature for example) and feature just as if the master branch had never moved forward -> the name of a branch passed as argument equals to the HEAD commit in that branch -> for example: -> git diff branch1 branch2 -> shows the differences between the latest commits in the branches -> commits can be identified by their hexadecimal strings of characters ids -> output -> diff --git a/test.py b/test.py	   | diff --git marks the beginning of a new comparison. Next, are the compared files, called a and b and then names of the actual files index 30f664c..5447a65 100644	   | files metadata (file hashes, mode identifier) --- a/test.py			   | --- and +++ are file markers. They are used to identify which lines belong to which file +++ b/test.py			   | /dev/null				   | file marker when the file is new or deleted @@ -423,4 +423,4 @@ def step6(self):   | where the changes occured. -423,4 means showing 4 lines (,4 -> for context) beginning with line 423 return True			   | |					   # this line is added for test 	    | -# hello 2				   | - line represents a line from file a which is different from the same line in file b					    \ No newline at end of file		    | when there are lines displayed without - or + it means that line is identical in both files +# hello 23				   | + line represents a line from file b which is different from the same line in file a					    \ No newline at end of file		    | -> git tracks file contents using hashes of their contents. If two files have the same content hashes, git might interpret that as a file rename. In this case --no-renames should be used. -> OPTIONS -> --staged / --cached -> shows the differences between the INDEX and the REPOSITORY -> --no-renames -> turns off rename detection -> HEAD -> shows the differences between the working directory and the HEAD commit in the same branch, effectively showing all staged and unstaged changes -> -w -> ignores whitespace changes -> GIT CHECKOUT [commit | branch | file] -> definition -> "Switch branches or restore working tree files" -> "Updates files in the WORKING TREE to match the version in the INDEX or the specified tree" -> the most common uses of this command is to switch to a branch or restore file(s) to their commited state. -2Q> if a commit is specified (hash/branch) -> moves the HEAD ref to point to the specified ref (either by branch or SHA), in the repository, essentially changing the current commit -> copies the current data from the REPOSITORY to the INDEX and WORKING AREA -2Q> if a commit is not specified -> copies the data from the INDEX to the WORKING AREA -2Q> applying these actions to the common uses -> switch to another branch -> git checkout mybranch (a commit is specified) -> moves HEAD to point to mybranch, which means that it indirectly points to the latest commit in mybranch -> copies the data from the commit, from the REPO (object database), to the INDEX and WORKING DIRECTORY, overwriting all files (because none was specified in particular). -> restore a file to its INDEX state -> git checkout myfile.txt -> copies the data from INDEX, to the WORKING DIRECTORY, overwriting ONLY THE SPECIFIED file. -> restore a file to its commited state -> git checkout mybranch myfile.txt -> copies the data from the commit, from the REPO (object database), to the INDEX and WORKING DIRECTORY, overwriting ONLY THE SPECIFIED file. -> used -> on commit -> effectively moves the HEAD to the specified commit -> the working directory is moved into a "detached HEAD state" -> it happens when a single commit is checked out -> it means that we are no longer on a branch -> any modifications (commits) to the project does not impact any of the branches -> solution -> discard changes made in this state -> simply checkout to a branch -> the commits made in this state will be garbage collected after a while -> keep the changes made -> create a branch for the detached HEAD state -> maybe merge the branch to master -> on file -> will update the file, or files to the version in the INDEX -> here 'file' shuold be understood as 'path'. It will restore the INDEX version of a file, a directory or the whole working directory. -> on branch -> all changes must be staged or commited before the checkout -> switches to specified branch -> the working directory will be updated to reflect the branch -> the new commits will be recorded on the current branch -> on both branch/commit and path -> updates the file to the commit version. -> OPTIONS -> -b [branch] -> creates the branch and switches to it										   -> all unstaged/uncommited changes existing will be moved to the new branch -> this is used for "quickfixes" -> quick modifications on a branch that extend so much that more work is needed, and at the same time, the branch has to stay free -> the already made changes can be checked out to a branch -> the previous branch will be restored to the last commit -> if the arguments [remote]/[branch] are passed, then the newly created branch is set to track the target remote branch. Equivalent of git branch [localBranch] [remote]/[branch] -> -f [branch] -> force the checkout even though there are uncommited changes in which case discards the changes. -> --track [remote]/[branch] -> creates the local equivalent of the remote branch and switches to it												 -> sets the newly created branch to track the remote branch -> --patch -> executes git checkout on a section of the file only (called hunks) -> GIT BRANCH -> without any argument supplied, lists local-only branches -> [branch] -> creates a new branch -> [branch] [sha] -> creates a new branch starting from the specified commit -> [localBranch] [remote]/[branch] -> creates localBranch -> retrieves the remote branch's history into the localBranch -> sets localBranch to track the upstream remote branch -> it is the correct way to retrieve a remote branch -> OPTIONS -> -m [oldbranch] [newbranch] -> renames oldbranch to newbranch -> if oldbranch is not supplied, then it renames the current branch to newbranch -> -a / -all -> lists both remote and local branches, and the position of HEAD -> -r -> displays the remote branches -> -d [branchname] -> deletes the target branch -> if there are unmerget commits, Git will raise an error and abort the deletion -> -D [branchname] -> forces the deletion of a branch -> -vv -> shows the local branches and what remote branches they are tracking, and if they are ahead or behind -> [localBranch] --set-upstream-to [remote]/[branch] -> sets the local existing branch to track the upstream branch from the remote repo -> achieves the same result as GIT BRANCH [localBranch] [remote]/[branch] with a few differences -> (below facts apply to git branch [localBranch] --set-upstream-to [remote]/[branch]) -> the localBranch has to exist. If it doesn't, raises an error. -> in order to work well, the remote branch has to be ahead or, at least equal, to remote master: reason: -> cloning pulls from remote master -> when created, the local branch is equal to local master, which is equal to remote master -> if remote master is ahead of remote branch, then local branch will be ahead of the remote branch it tracks -> GIT SWITCH [branch] -> switches to the branch. It is the same as a 'git checkout [branch]' -> OPTIONS -> -c -> creates the branch and switches to it -> GIT RESTORE [file] -> restores the file(s) from the WORKING AREA to their INDEX state. -> OPTIONS -> -S / --staged -> restores the files from INDEX to their state in HEAD, leaving the WORKING AREA unaffected. -> --source=[commit] -> specifies a different commit to use for restoring the file(s) in the WORKING AREA -> -W / --worktree -> restores the files from the WORKING AREA to their state in INDEX. -> the default option -> use case: git restore --source=HEAD -SW. -> reverts the WORKING AREA and the INDEX to their state in the REPOSITORY -> GIT TAG [tag] -> creates a tag for the current commit -> without any options, shows a list of existing tags -> git tags will always point from the last commit, forward -> OPTIONS -> -a -> creates an annotated tag -v -> verifies a tag -s -> creates a signed tag -m [message] -> adds a message to the tag -> GIT MERGE [branch] -> merges the supplied branch into the current one -> Use case: switch to master branch then use the command on a branch. That will bring the content from the supplied branch into master. -> merging a branch into another won't delete any of them -> merging creates a new commit which has both merged commits as parents and moves HEAD (and implicitly the branch pointer) to the new commit -> when merging two files a conflict may appear which must be solved manually -> appears during a merge, when there are changes between the same lines in a file, or there are changes regarding the file altogether (file deleted or moved) -> at that point, the merging commit no longer brings 'updates' to the file, but it brings a conflicting change, and Git can't decide which change has priority. -> Git compares the contents of the merging commits, with the content of the ancestor commit of both branches, to detect whether the changes introduced by the merge are conflicting or not. -> the changes are contained within the file markers <<<<<<< >>>>>>> and separated by ============ -> after the conflicts have been solved, the edited files have to be staged and commited, and this is how the merge commit is completed. -> in this context, add and commit have only merge-tied effects (for example, the commit won't be displayed as a separated commit from the merge commit) -> if a branch has been merged with another -> one branch moves ahead having all the content from both -> the other remains as it is										  -> if these two branches are merged again -> the first one already has all the content from both from the earlier merge -> creating a second merged commit identical to the one already existing would be wasteful -> the second branch pointer is simply moved to the merged commit -> this is called a "Fast-Forward" -> [remote]/[remoteBranch] -> merges the supplied remoteBranch of the remote, into the current branch -> OPTIONS -> --abort -> aborts the merging process and returns the working directory in its pre-merge state. -> GIT MERGETOOL -> opens the merge tool in case of merging branches and conflicts. -> GIT REBASE [branch] -> rebases the current branch on top of the branch supplied as argument (target). -> the target branch is unaffected -> the latest commit in the target branch becomes the BASE commit of the current (rebased) branch -> the latest commit from the target branch is pulled and placed between the former base and the first commit after base, effectively becoming the new base -> conflicts may appear and they must be solved -> the rebased commits are identical copies of the commits from the rebased branch -> GIT cannot "move" commits -> everything is identical except commit parents -> the rebased branch pointer will be moved to the rebased branch (copied commits) -> The original commits from the rebased branch will no longer have a branch pointer and will be garbage collected -> BASE -> is the shared commit between the two branches. Effectively, is the first commit of a branch (or where the project is branching). -> base commit won't be rebased as the state it describes has already existed in the history of the project. -> REBASING vs MERGING -> both commands have the same general effect: they merge two branches -> MERGE -> keeps the project's history intact even though confusing -> it merges both branches' histories yet shows the commits as they were made. -> REBASE -> rewrites the project's history -> it appears that the changes in the rebased branch were made after the changes in the target branch, although they were made simultaneously (different timelines) -> use cases -> clean up history before sharing a branch -> pull changes from a branch into my branch without performing a merge -> commit SQUASH -> its purpose is to combine all the commits of the source (current) branch into one -> done by using -i interactive rebase mode -> squashing is accomplsihed by -> rebasing the current branch onto the merge-base commit (the common ancestor commit of current branch with master) -> rebasing onto the merge-base commit won't create conflicts (as merge-base commit already is base of branch) and -i will allow editing the rebasing process -> during rebase, one commit, usually the oldest will be "picked" (will remain) and all the others will be "squashed" (merge into the previous until all will be merged into the picked one) -> the final commit message will be a combination of all the other commit messages but they can be edited/removed. -> OPTIONS -> -i / --interactive [commit] -> starts an interactive rebasing process -> allows the editing of the repository's history, from onwards. won't be modified, but the very next commit, will. -> the list of the commits is inverse of the order they have been created -> process -> each commit is a line in the list and is preceded by a command (pick, reword, squash, etc...) -> for each commit, the command (by default, pick) can be changed so the desired result is obtained -> the command squash combines (merges) two commits together, the squash commit and the previous one in the list. -> if in the original history were conflicts, during rebase squash they will have to be solved yet again. -> after a conflict is solved (edited file), the modifications are staged and git rebase --continued is ran so the rebase process can go on. -> as usual, all these new or copied (picked) commits are copies of the original ones. -> if the rebase process is completed, the new commits will be the 'new' history while the old commits will be garbage collected. -> if the interactive rebase process is completed, the project will have a whole new history. -> GIT CHERRY-PICK [commitSHA] -> applies the changes introduced in the target commit to the HEAD commit. -> it finds the changes done from the commit previous to target commit, to target commit, and replicates the same changes to the HEAD commit. -> it is different from merge because -> merge adds all the differences from both commits into one commit that contains everything. -> cherry-pick -> adds only the differences which occured between target and previous-to-target commits, to the head commit, while leaving unaffected any other files -> just replicates those changes to the HEAD commit, without merging the commits -> use cases -> a bugfix which applies to multiple versions, each version having its own branch -> used when a merge is impossible -> GIT REVERT [commit] -> reverts the exact specific changes introduced by the specified commit. -> it doesnt affect the history (the commits are left untouched) -> it adds a new commit to the repo with the reverted changes -> it does NOT bring the REPOSITORY to the state from before of the specified commit (doesn't rewind) -> for example, if commit A adds line 1 and 2 to file.txt and commit B, adds lines 3 to 10, reverting commit A will result in file.txt containing only the lines 3 to 10. -> very susceptible to conflicts, depending on the project's history -> it doesn't revert structural changes to the project (like merging branches) -> GIT RESET ['commit'] ['file'] -> "moves commits from history into working directory/staging area or deletes them" -2Q> actually, performs two actions -> first: moves the branch ref that HEAD is pointing to, to the specified commit, basically changing the current commit in the REPOSITORY. -> second: depends on the options -> OPTIONS -> --soft -> "moves the commits back into the staging area"							                  | This first arrow is how most sources describe --soft, while the 2Q arrow describes, what it actually happens. While the overall result -2Q> second action: only moves the branch ref to the specified commit. Doesn't afffect the INDEX or the WORKING AREA. | it is basically the same, the difference is in how it happens. The commits are not 'moved' into the INDEX, it just seems like it. -> --mixed -> default option if none specified										                  | Same story here, only that after the current commit is changed, the INDEX is updated. -> "moves the commits back into the working directory"								                  | An analogy to how --soft is described above can be applied here. -2Q> second action: copies the changes from the commit you've just moved to, only to the INDEX, leaving the WORKING AREA unaffected. |							     -> common usecase -> git reset HEAD -> unstages the staged changes -2Q> the branch ref stays where it is because no other commit has been specified (can be seen as moving it to the same place it already is), and updates the INDEX with data from the REPOSITORY, overwriting any modification. -> --hard -> "deletes the changes from all the commits newer than the specified one"									| As a note on Git reset (not only--hard), it is important to know how git reset actually works, because as most sources describe it, -> "effectively makes the specified commit the latest, and moves HEAD to it"							       | it is implied that git reset is limited to a branch's history. While it is true that the most common usage of -2Q> second action: copies the changes from the commit you've just moved to, to both INDEX and WORKING AREA. | this command is to modify a branch's history, like reverting some commits, git reset has no such limitations. -2Q> effects -> hard-resetting to an older commit will result in the subsequent commits becoming unreachable and will be garbage collected.| It can be used from any branch, on any commit, even belonging to other branches, and the effects can be confusing and destructive -> completly alters the state of the project											| For instance, Git reset can be successfully used to overwrite entire branches with commits from another branches, or similar destructive operations. -> common usecases -> revert the whole project to an earlier state (previous commit) -> git reset --hard HEAD -> discard all uncommited changes from working directory and index. -> can cause data loss, so use with care -> --patch -> executes git reset on a part of the file only (called hunk) -> GIT PRUNE -> removes the unreachable objects from the objects database -> a repository maintenance command which performs a garbage collection task -> Git gc is the recommended alternative to git prune, because it can perform additional repository optimization actions. -> GIT GC -> "Cleans up unnecessary files and optimizes the local repository" -> please read the official documentation on this one :)		-> GIT FILTER-REPO -> command not officially added to Git, available as a separate tool		                  -> command used to completly alter the whole history of the repository		   	           -> basically specifies a file (or path). Will keep that file and will delete everything else in the repo 		   		   -> used as a last resort		   		   -> one use case would be completly removing a file from the repository and its history.		   		   -> OPTIONS -> --path specifies a file			                      -> --invert-paths -> the paths are inverted						                -> the specified path will be deleted						                -> all the other (implied paths) are kept		-> GIT REMOTE -> command used to manage the 'remote relationships' between the local repository and other shared repositories			      -> with no arguments or options, lists the remotes for the current repository -> OPTIONS -> -v -> lists additional information about the remotes (such as the URLs) -> ADD [name][uri] -> adds a new remote from the [uri] to the project, locally named [name] -> can be used to clone a remote repository, however, it should be proceeded carefully: (you better use git clone. Less of a headache) reason: -> a branch with no history (on a newly initiated repo) -> is seen by git as unexisting since there are no commits the branch ref can point to															      -> cannot be set to track a remote branch, because it basically doesn't exist, so in order to track a remote branch, it has to have at least 1 commit -> by default, Git doesn't allow merging a local branch with the remote branch it is tracking, if they have different histories (the 1 commit from above). -> for the above reasons, creating a repo from scratch (git init) and adding a remote to it won't allow you to actually get the remote repo (unless using --allow-unrelated-histories) -> this case applies when trying to use "--set-upstream-to", like -> there are different ways to clone a remote repository without using git clone though: -> git checkout -b [branch] --track [remote]/[branch] -> -b instructs git to create the branch then set the upstream branch -> git branch [localBranch] [remote]/[branch] -> creates the branch and sets it to track the remote branch -> git switch [branch] -> right after git fetch -> conditions -> there must be a link to a remote repository -> the remote has to be fetched locally -> try to git switch to one of its branches -> git will automatically create a local branch with the same name -> set the newly created local branch to track its remote counterpart -> pull the remote branch to it																												     -> switch you to it -> NOTE THAT the above methods apply whenever you need to create a local branch that tracks a remote branch. Not necessarily if you have a new repo. -> another (and perhaps the intended) usage of this command, is to add a remote link to another fork of the same repository. This would allow one to concurently work with different forks of the same project -> UPDATE -> updates the remote ref branches for all remote repositories -> effectively fetches the changes -> SHOW [remote] -> shows info about the target remote -> PRUNE [remote] -> removes remote references that are no longer on the remote -> equivalent of git fetch --prune [remote], except it doesn't fetch anything from the remote -> this command does NOT delete the local branch which tracks a remote branch that no longer exists. Only the tracking reference to that branch is deleted. -> REMOTE -> is a copy of the Git repository, located somewhere else, usually the cloud -> the purpose of a remote is to -> make public a repository -> allow multiple people work on the public repository -> provide a common synchronization point for all people involved -> a local repository might have 'remote relationships' with public repositories -> 'public' means 'shared', because it refers not only to repositories made public on the internet, but to repositories shared in any other way -> if these relationships exist, the public repositories are 'remotes' of the local repository -> if 'the repo has remotes', then it is possible to sync the local repository with the remote ones by pushing, pulling, etc.															 -> so, these remote relationships are used to track the remote repository's changes and to synch the local repository with it			               -> the actual remote tracking -> when a remote relationship is created, a new folder for this remote is created in .git/refs/remotes/ -> this folder contains the remote-tracking branches -> also called tracking branches, remote reference, remote branch reference, etc. (from here onward we will call it 'remote ref' for simplicity) -> these are also local references -> their purpose is to reflect the state (track) of the remote branch (sequence of commits) with the same as theirs. -> can be thought of as a local copy of a branch reference of the remote repository. -> a link between the local branch reference and the remote ref can be created -> if manually created the message 'local branch set to track the upstream branch' :)																		    -> when it is created, then the local branch will track the remote branch (now called upstream branch)																		     -?> not sure how Git stores this link, maybe based just on commits and the references between them																		     -> basically the tracking between a local and a remote repository is just the tracking between their branches. 																		     -> these links can be displayed with git branch -vv																		     -> Git tracks the differences between local and remote branches by: -> looking at the local branch ref and checks what commit hash it is pointing at							              																		         -> looking at the remote ref that the local branch is tracking and checks what commit hash it is pointing at							              																			 -> now it can calculate how many commits ahead or behind the local repo is compared to the remote (effectively the difference in commits) -> REMOTE/HEAD ref -> reference that represents the default branch of the remote repository -> determines which branch will be downloaded when the repo is cloned -> REMOTE FLOW -> a Git repository will obtain a remote link -> when cloning the remote repository which will automatically add a link to "origin", which is the cloned remote repository -> by manually adding a remote link using $git remote add [name][uri] -> used if remotes to different forks of the same remote are desired <> -> once a remote link has been created -> git fetch [remote] <> -> usually, when cloning, the main branch will be retrieved to local -> git branch [newlocalBranch] [remote]/[branch] -> to locally replicate a remote branch and track it											               -> <> -> git pull | -> the repos are synchronized either by pushing or pulling (fetch + merge) -> git push | -> GIT PUSH [remote] [branch] -> with no arguments, pushes the changes of the local current branch to the upstream branch of the remote repository. If the branch doesn't exist, it creates it. -> pushes the changes upstream, towards the remote repository -> git push is aborted when there are merge conflicts between local and remote -> [remote] is the upstream remote repository, [branch] is the remote branch we push to, from the current local branch -> [remote] [localbranch]:[remotebranch] -> creates the new remotebranch for the remote (a new remote branch, on the online repository, with no local equivalent) -> pushes the changes from localbranch to remotebranch -> no local branch will be set to track the remote branch -> [remote] :[remotebranch] -> deletes the remote branch -> OPTIONS -> -u / --set-upstream [remote][branch] -> sets the upstream branch and pushes the changes to it. -> pushes the whole branch to the remote (creates it on the remote) if it doesn't exist -f -> force a push -> the remote repo will be updated regardless of the conflicts that may appear -tags -> pushes tags. Tags aren't pushed by default -> GIT PULL -> is a combination between GIT FETCH and GIT MERGE commands -> automatically fetches and merges the changes from the remote branch to the local branch which tracks it			   -> OPTIONS -> --rebase -> used when the upstream branch gets rebased and git pull would result in conflicts -> uses reflogs to search the common ancestor of the upstream and local branches (even thouugh it had been squashed) -> resequences the commits in the local branch by pulling the remote commits and rebasing the local commits on top of them -> GIT FETCH -> fetches the refs (branches, HEAD) and all the objects necessary to rebuild the history (the current state of the remote), from a remote (by default origin) -> effectively downloads the changes to local -> in case of a conflict, the remote branch will be separate from the local branch -> [remote] -> fetches the changes from the target remote -> [remote][branch] -> fetches the changes from the target branch of the specified remote -> OPTIONS -> --all -> fetches from all remotes --prune -> first, it removes remote references that are no longer on the remote, then performs fetching -> without any arguments supplied, it performs this action for all remotes -> this command does NOT delete the local branch which tracks a remote branch that no longer exists. Only the tracking reference to that branch is deleted. -> GIT RM [file] -> deletes the file from both the WORKING AREA amd the INDEX -> if the file is untracked, git rm cannot be used to delete it. -> OPTIONS -> git rm --cached -> removes the file from the INDEX only, keeping it in the WORKING AREA -> turns the file into an UNTRACKED file if the change is commited (commiting would remove the file from the REPOSITORY as well). -> git rm -f -> forces the execution of git rm		-> GIT MV [file] [file] -> moves/renames the file -> Note that -> moving(renaming) a file manually (before staging the change), will be interpreted by git as a deletion + new file. However, when this file reaches the staging area, Git will compare the content of the files in the REPOSITORY with the content of the files in the INDEX and will understand it is a rename/move operation (not delete + add). It is also can detect the renaming/moving operation, even though there are slight changes to the contents of the file. -> This whole manual operation can be skipped by git mv. It esentially moves(renames) the file in the working directory and stages this change in a single operation. -> Note that manually moving a file (interpreted as a deletion) has to be added to the staging area (deletion is a change which has to be added to index). -> GIT BISECT -> tool that helps in identifying the commit which introduced issue-causing code. -> it does that by specifying a good commit, and a bad commit and will check, either manually or automatically, each commit in between to find the one that introduced an issue -> operation -> git bisect start -> starts the bisect process -> git bisect good -> identify the good commit | this two commands are first used to identify the 'limit' commits of the bisecting process. The good and the bad one. -> git bisect bad -> identify the bad commit  | they are also used in the manual process to indicate if a commit is good or bad -> git bisect run -> executes the automated bisect process -> basically git will execute a command (cli shell), for each commit -> based on the status code returned by that cli command, will identify the commit as good or bad. -> For example: -> there is a script, script_test.py that tests a particular piece of code called program.py, which is tracked by git. -> git bisect run script_test.py will be executed on each commit that program.py went through. -> if script_test.py returns a 0 status code, the commit is good, if script_test.py returns a non 0 status code, the commit is bad -> git bisect reset -> ends the bisect process. -> during the manual bisecting process, each commit has to be evaluated manually, git will only keep track of the results -> git bisect does not evaluate the start and end commits. -> PLUMBING COMMANDS -> git hash-object [object] -> calculates the SHA1 value of an object -> OPTIONS -> --stdin -> the supplied value is taken from STDIN -> git cat-file [sha] -> displays details about a git object -> OPTIONS -> -t -> displays the type of the object whose hash is supplied -> -p -> pretty prints the object -> git count-objects -> shows the number of objects in the current project -> git show-ref [reference] -> displays all the refs containing the target word in their name -> git merge-base [branch][branch] -> shows the common ancestor commit of the two branches -> git ls-remote -> shows the remote references of the repository -> shows the remote references even without $git remote update -> CONFIGURATION -> Git configuration is handled at multiple levels -> are hierarhical -> the more specific levels override the more general ones -> Repository Configuration > Global Configuration > System Configuraion -> levels -> Repository Level -> also called the 'local' level -> applies only to the repository it is located in (specific for each repository) -> config file is located in .git/config (repository directory) -> has priority over all the other levels -> Global Level -> also called 'user account' level -> config file is located in user_dir/.gitconfig -> applies to all the projects of the system user -> System Level -> applies to all projects and all system users -> located in the git installation folder -> it usually handles more system-oriented config attributes (like the default text editor or the behaviour of "pull" command) rather than repository-oriented config attribute, like --global and --local configs handle (like the username or email address) -> a config item can be set at any level, however the most specific level has priority -> for example: -> it is possible to set a global user "Jim", but a given repository to have a user "John" -> the given repository will have the user 'John' configured and all the other repositories will have the user 'Jim' configured. -> git --version -> displays the git version -> configuration file structure -> [section] -> a general area to group up config keys -> key = value -> the key is a config item -> the value is the value for a specific config item -> GIT CONFIG [--conflevel][--action][section.key["value"]] -> the command used to modify the config files, thus configuring Git. -> git config explained -> --conflevel -> specifies the config level, which basically specifies which config file to edit -> --action -> performs a specific action -> for example: -> --list -> git config --local --list -> lists the repository config -> section -> identifies the section in the config file where the key is found -> section are used to better organize the contents of the config file. -> there are also git config actions that can be applied to all the config items, by specifying the section. -> key -> the config item whose value is to be changed or retrieved -> value -> the new value to be set to the config item -> for example -> git config    --local         user.name  "My Name" |-git command-|-conflevel-|-section-|-key-|--value--| -> this command sets the "My Name" value to the 'name' config item, found in the 'user' section in the repository config file. -> specifying a config type -> git config --system -> indicates a SYSTEM config item -> Example: git config --system user.name "Name Surname" -> git config --global -> indicates a GLOBAL config item -> Example: git config --global user.name "Name Surname" -> git config --local -> indicates a REPOSITORY config item -> it is the default config level if a config type is not specified -> Example: -> git config --local user.name "Name Surname" -> same as: git config user.name "Name Surname" -> setting a configuration item -> git config section.key "Value" -> Example: git config --local user.name "Name Surname" -> sets the username for the current repo -> retrieving a configuration item -> git config section.key -> NO value for the item must be specified -> if a value is specified, then the value will be SET for the item -> Example: git config --local user.name -> retrieves the username of the current repository -> removing a configuration -> git config --unset [--conflevel][section.key] -> removes the config key specified from the file specified -> other commonly used commands -> git config [--conftype] --list -> displays the configurations -> git config --list --show-origin -> shows the configuration settings that are applying in the respective context where the command is issued from, and the file where they are being read from -> git config --global --edit -> opens the config file specified in a editor for editing -> git config --global --remove-section -> removes the entire config section from the file specified -> commonly configured items -> user.name "Name Surname" -> user.email "email@domain.com" -> core.editor "cli_command" -> sets the default text editor -> "cli_command" is the shell command to launch the editor -> when a file is to be modified in Git, the command "cli_command" will be executed -> help.autocorrect [0|1] -> autocorrects the commands inputted in bash after 0.1 second. -> set to zero to disables autocorrect -> color.ui auto -> uses colors to display info in CLI -> core.autocrlf true|false|input -> crlf - carriage return line feeds -> true: converts crlf (typically used in windows) into line feeds and stores them into a repository, and converts them back out -> false: stores crlf into a repository as they are, without converting them -> input: converts crlf into line feeds when storing them but doesn't convert them on the way out of the repo -> http.sslVerify [true|false] -> by default, Git verifies the SSL certificate of the site where a repository is cloned from -> if the site doesn't have a SSL certificate, it is expired or is self-signed, Git doesn't allow cloning the repository -> setting the http.sslVerify attribute to "false" will instruct Git to skip SSL certificate verification -> this is a big security risk -> core.longpaths [true|false] -> usually configured at system level -> configured on Windows OS where Git has a limit of 260 chars for a filename -> setting in to TRUE removes that limit, and the new limit becomes 4096 chars -> ALIASES -> an alias is a shortcut for a command. -> aliases are created with "git config" -> when an alias is created, the config file is edited to add a key=value pair under [alias] section, where 'key' is the alias and 'value' is the full command -> git config [--conflevel] alias.[newalias] "command --options" -> "git newalias" will now be the equivalent of "git command" -> Example: git config --global alias.goad "log --graph --oneline --all --decorate" -> the aliases are stored in the config files.

-> creating git CUSTOM commands -> a Git custom command is an executable script file -> its name must start with git-. Example: git-mycommand -> the location of the script file must be registered in the $PATH environment variable, so it can be found by Git. -> git mycommand -> git searches the locations in $PATH to find git-mycommand file -> if it is executable, git will execute the script from inside -> SUBMODULES -> it is a Git feature that provides a method to integrate code from another repository into the current repository -> a submodule is a Git repository in itself -> can be edited and updated like a regular repository -> can have multiple branches which can be switched -> when a repository has been added as a submodule to another repository, it won't track a remote branch, but a remote commit. This is done in order to avoid accidental updates -> can contain other submodules -> working with submodules -> adding a submodule to the repo -> git submodule add   -> adds the repository from the url to the current repository, under the directory directory_name -> basically clones the submodule repo into the directory and then adds a remote-like connection to another repository in .gitmodules file -> after that, git add and git commit to add the newly downloaded files to the repo -> when submodules are added, they are referenced in the .gitmodules file -> file which holds all the references to submodules -> example: [submodule "dummy-project"]                                     | the reference name path = dummy-project	                             | the path from repo's root where the submodule is																				             url = https://github.com/gitpractice-w/dummy-project.git | the url where the submodule has been cloned from -> this file will be pushed to remotes, so anyone working on a project would know what submodules have been referenced, so they can also use them -> after the submodule has been added, git status shows "new file:  dummy-project". This is actually a reference to the commit of the repository used as submodule. -> config items for submodules -> git config --global status.submoduleSummary true -> instructs git status to show info about the submodule repository -> Shows the updates from the submodule which haven't already been commited to the main repo Submodule changes to be committed:

* dummy-project 0000000...b92f907 (4): > Merge pull request #3 from WessCoby/via-gui -> git config --global dif.submodule log

-> cloning a repo with submodules -> git clone -> git submodule init -> initializes the submodules from the .gitmodules file -> git submodule update -> updates the initialized submodules -> removing submodules -> git submodule deinit -> deinitializes the sumbodule -> the files from the corresponding directory are removed -> doesn't modify the .gitmodules file -> permanently -> git submodule deinit -> git rm  | remove the submodule's directory and updates the .gitmodules file -> git commit		  | -> working with nested submodules -> git clone --recursive -> clones the repository -> goes through the submodules tree, initializes and updates all submodules -> git submodule foreach 'command' -> applies the command to all submodules (regular or nested) -> basically goes into the submodule folder and executes the command -> working remotely with submodules -> git pull -> integrate the changes from the teammates						 | these three commands are used to update the repository from the remotes -> git submodule sync --recursive -> synchronizes the .gitmodules file with the remote		 | when working with submodules. Basically, git pull updates the repository itself -> git submodule update --init --recursive -> initializes any new submodules if there are           | and the other two commands update the submodules -> recursively updates all submodules (regular or nested) | -> best practice -> as for regular repository, when updating a submodule, first git pull. -> when a submodule has been modified and changes commited -> git status in parrent repo will display (new commits) available for the submodule and a commit must be made so the parent would update its submodule reference commit. -> before pushing the updated parent repo, the submodule must be pushed FIRST. Otherwise the parent repo would reference a submodule commit that isn't available for anyone -> this can be done by configuring git to do this automatically with git config --global push.recurseSubmodules on-demand -> when pushing the parent repo, git will check if there are pushes needed for submodules and if there are, will do them -> Terms: -> FORK -> a remote clone of a remote repository. -> used to work with when the original remote repo requires permissions for regular operations -> usually, it is used -> to update the original repository -> the remote clone can be updated freely -> a pull request will be made to the original repo to pull the modifications from the edited clone. -> the pull request and changes will be reviewed and the changes may or may not be brought to the original repository. -> to fork a project into a different project -> not a concept of Git itself, but of the public GIT hosting services -> PULL REQUEST -> a pull request is used to update a remote repo, which requires permissions to be updated. -> basically, a pull request is used to 'ask' the owner of the remote repo to pull the changes from us (e.g. from our fork). -> a pull request may be used for different operations, based on the Git service provider -> pulling the changes from a fork to the original repo -> merging the already pushed changes from a remote branch to another branch (usually master) -> REPOSITORY -> term usually used for -> a project tracked by Git. In this case it describes the whole project with all its areas (repository, index, working directory, stash) -> in the context of a project tracked by git, it is the .git folder (the repository area) -> PORCELAIN -> common commands used more frequently -> PLUMBING -> uncommon commands used rarely, or in scripts of some kind -> FILE STATES -> untracked -> untracked by Git -> it doesn't belong to the git repository -> tracked -> COMMITED -> files saved in a snapshot (git commit) -> MODIFIED -> files which have been modified from their last commited version -> STAGED -> modified files marked to be added in the next snapshot with git commit

-> BEST PRACTICES -> before pushing changes to the remotes -> always fetch -> merge and solve conflicts -> then push -> before merging a branch with the main branch, first fetch the changes from the remote main to the local main -> never rebase shared commits -> a common .gitignore file to prevent unwanted ignores -> README.md file in the root directory should keep all important info about the project -> frequent samller commits vs one giant commit -> coordination with the teams before large refactors -> do not rebase on a public branch -> check team guidelines about rebase -> while GIT tracks changes to any kind of file, it was not designed for/its use is not recommended for binary files. -> never change shared history (like rebasing shared history) -> lots of early commits which will be later rebased interactively (squashed) are better than one large commit

-> REFERENCES -> https://stackoverflow.com/questions/67779477/how-does-git-know-there-is-a-conflict -> https://stackoverflow.com/questions/20106712/what-are-the-differences-between-git-remote-prune-git-prune-git-fetch-prune -> https://stackoverflow.com/questions/22575662/filename-too-long-in-git-for-windows -> https://git-scm.com/docs/git-gc -> https://git-scm.com/book/en/v2/Git-Branching-Remote-Branches -> Pluralsight's Git courses -> https://css-tricks.com/git-pathspecs-and-how-to-use-them/ -> Atlassian Git tutorials