Essential Linux and Git-GitHub Commands

LINUX COMMANDS

cd: changes the current working directory to the user's home directory.
cd ..: changes the current working directory to the previous directory.
cd [directory]: changes the current working directory to the specified directory.
pwd: displays the current working directory.
ls: lists the contents of the current directory.
ls [directory]: lists the contents of the specified directory.
ls -a: lists all files and directories (including hidden files) in the current directory.
ls -l: lists the contents of the current directory with detailed information.
ls -lh: lists the contents of the current directory with detailed information, and displays file sizes in a human-readable format.
mkdir [directory]: creates a new directory with the specified name.
mkdir -p [dir1]/[dir2]/[dir3]/.../[dir n]: creates nested directory.
chown [user:group] [file]: changes the owner and group of the specified file.
chmod [permissions] [file]: changes the permissions of the specified file.
rm [file]: removes the specified file.
rm -r [directory]: removes the specified directory and its contents.
tree [directory]: displays a hierarchical tree view of the specified directory and its contents.
find [directory] -name [filename]: searches for files with the specified name in the specified directory and its subdirectories.
locate [filename]: searches for files with the specified name using an indexed database.
which [command]: displays the full path of the specified command.
grep [pattern] [file]: searches for lines in the specified file that match the specified pattern.
less [file]: displays the contents of the specified file, allowing the user to navigate through the contents with arrow keys.

File Manipulation

touch [file]: creates a new empty file with the specified name.
diff [file1] [file2]: displays the differences between the contents of file1 and file2.
cat [file]: displays the contents of the specified file.
cp [file1] [file2]: copies the contents of file1 into file2.
cp -r [directory1] [directory2]: copies directory1 and its contents to directory2.
cp -p [file1] [file2]: copies file1 to file2, preserving the original file's permissions, ownership, and timestamps.
mv [file1] [file2]: renames or moves file1 to file2.
mv -i [file1] [file2]: renames or moves file1 to file2, prompting the user if file2 already exists.
rm -f [file]: forcefully removes the specified file without prompting for confirmation.
rm -i [file]: prompts the user for confirmation before removing the specified file.
rm -rf [directory]: forcefully removes the specified directory and its contents without prompting for confirmation.
tar -cvzf [archive name] [directory]: creates a compressed tar archive of the specified directory.
tar -xvzf [archive name]: extracts the contents of the specified compressed tar archive.
split -b [size] [file]: splits the specified file into multiple smaller files with the specified size.
join [file1] [file2]: joins the specified files into a single file.
awk: a scripting language for text processing that can manipulate files line by line.
sed: a stream editor for performing basic text transformations on an input stream.

User and Group Management

useradd [username]: creates a new user with the specified username.
userdel [username]: deletes the specified user.
groupadd [groupname]: creates a new group with the specified name.
groupdel [groupname]: deletes the specified group.
passwd [username]: sets the password for the specified user.
usermod -aG [groupname] [username]: adds the specified user to the specified group.
id [username]: displays information about the specified user, including their UID and GID.
groups [username]: displays the groups to which the specified user belongs.
chgrp [groupname] [file]: changes the group ownership of the specified file.
chown [username] [file]: changes the owner of the specified file.

System Information

uname: displays information about the system kernel.
top: displays real-time information about running processes.
top -p [PID]: displays real-time information about the specified process ID.
ps: displays information about running processes.
ps -ef: displays detailed information about all running processes.
df: displays disk usage information.
du: displays the disk usage of files and directories.
df -h: displays disk usage information with file sizes in a human-readable format.
htop: an interactive process viewer that displays real-time information about running processes.
free -h: displays information about system memory usage in a human-readable format.
ifconfig: displays network interface configuration information.
netstat: displays information about active network connections and associated processes.
netstat -tulpn: displays information about active network connections and associated processes.
iostat: displays I/O statistics for storage devices and partitions.
vmstat: displays virtual memory statistics, including memory usage, page activity, and CPU usage.
ip: displays and manipulates network interface information.

System Management

sudo [command]: executes the specified command with elevated privileges.
apt-get install [package]: installs the specified package.
apt-get remove [package]: removes the specified package.
apt-get update: updates the local package index.
apt-get upgrade: upgrades all installed packages to their latest versions.
apt-get dist-upgrade: upgrades the distribution to the latest version.
apt-get autoremove: removes all packages that are no longer needed by any installed packages.
reboot: restarts the system.
shutdown: shuts down the system.
reboot -h now: shuts down the system immediately.
shutdown -h now: shuts down the system immediately.
crontab -e: opens the user's crontab file for editing.
cron -r: removes the current user's crontab file.
systemctl start [service name]: starts the specified system service.
systemctl stop [service name]: stops the specified system service.
systemctl restart [service name]: restarts the specified system service.
journalctl: displays system logs.
iptables: a powerful firewall tool for managing network traffic.
sysctl: allows the user to modify and query kernel parameters at runtime.

at: schedules a command to be executed at a specific time.

GIT AND GITHUB COMMANDS

Setting Up

git config --global user.name "[username]": sets your username for Git.
git config --global user.email "[email]": sets your email address for Git.
git init: initializes a new Git repository.
git config --list: displays a list of all Git configuration settings.
ssh-keygen: generates a new SSH key pair for secure communication with GitHub.

Working with Repositories

git clone [repository URL]: clones a repository from GitHub.
git status: displays the current status of the repository.
git add [file]: stages the specified file for commit.
git add -A: stages all changes, including deleted files and renamed files.
git commit -m "[commit message]": commits the staged changes with a message.
git commit --amend: modifies the previous commit with staged changes.
git commit -a: commits all changes, including modifications and deletions, without staging.
git push: pushes the committed changes to the remote repository.
git pull: pulls the latest changes from the remote repository.
git reset [file]: unstages the specified file.
git reset --hard: resets the working directory to the last commit and discards all changes.
git stash: saves the current changes temporarily to the stash.
git stash apply: applies the last stashed changes to the working directory.
git stash save [message]: saves the current changes temporarily to the stash with a custom message.
git log: displays the commit history of the repository.
git log --graph: displays the commit history as a graph.
git log --oneline: displays the commit history with one-line messages.
git log --author=[author name]: displays the commit history filtered by the specified

Branching and Merging

git branch: displays a list of branches.
git branch [branch name]: creates a new branch with the specified name.
git branch -a: displays a list of all local and remote branches.
git branch -d [branch name]: deletes the specified branch.
git checkout [branch name]: switches to the specified branch.
git checkout -b [new branch name]: creates a new branch with the specified name and switches to it.
git merge [branch name]: merges the specified branch into the current branch.
git merge --abort: aborts a merge in progress.
git merge --no-ff [branch name]: merges the specified branch into the current branch with a commit message, even if it can be fast-forwarded.
git merge --no-commit [branch name]: merges the specified branch into the current branch, but does not commit the changes.
git merge --squash [branch name]: merges the specified branch into the current branch, but does not create a merge commit.
git rebase [branch name]: reapplies commits from the specified branch onto the current branch.
git rebase -i [commit hash]: starts an interactive rebase of the current branch, allowing the user to modify commits, delete commits, or squash commits.
git rebase --onto [new base] [old base] [branch name]: moves the specified branch onto a new base branch, discarding any commits that are only reachable from the old base branch.
git cherry-pick [commit hash]: applies the changes from the specified commit onto the current branch.

Collaborating with Others

git remote add [name] [repository URL]: adds a remote repository with the specified name and URL.
git remote set-url [name] [new URL]: changes the URL of a remote repository.
git remote -v: displays a list of remote repositories.
git fetch: retrieves the latest changes from the remote repository.
git fetch --all: fetches the latest changes from all remote repositories.
git fetch [name] [branch name]: fetches the latest changes from the specified branch of the remote repository.
git merge [name]/[branch name]: merges the specified branch from the remote repository into the current branch.
git push [name] [branch name]: pushes the committed changes to the specified branch of the remote repository.
git push [name] :[branch name]: deletes the specified branch from the remote repository.
git push --tags: pushes all tags to the remote repository.
git push [name] --force: forces a push to the specified branch of the remote repository, overwriting any conflicting changes.
git push [name] --tags: pushes all tags to the specified remote repository.
git clone --depth=1 [repository URL]: clones a repository from GitHub with only the latest commit history.
git remote rename [old name] [new name]: renames a remote repository.
git remote remove [name]: removes a remote repository.
git pull --rebase: pulls the latest changes from the remote repository and reapplies local commits on top.

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