Linux and Git-GitHub Cheat Sheet

here's a basic Linux file system commands cheat sheet:

Navigating the File System:

pwd: Print working directory (displays the current directory).
ls: List files and directories.
- ls -l: Long format, shows detailed information.
- ls -a: List all files, including hidden files.
- ls -lh: Long format with human-readable file sizes.
cd: Change directory.
- cd ..: Move to the parent directory.
- cd ~: Move to the home directory.
mkdir: Create a new directory.
rmdir: Remove an empty directory.

Working with Files:

touch: Create an empty file.
cp: Copy files or directories.
- cp source destination: Copy a file.
- cp -r source destination: Copy a directory recursively.
mv: Move or rename files or directories.
rm: Remove files or directories.
- rm file: Remove a file.
- rm -r directory: Remove a directory and its contents recursively.
cat: Display the contents of a file.
more: Display the contents of a file page by page.
less: Display the contents of a file with backward navigation.
head: Display the beginning of a file.
tail: Display the end of a file.
nano or vim: Text editors to create and edit files.

File Permissions:

chmod: Change file permissions.
chown: Change file ownership.

Searching:

grep: Search for a pattern in files.
find: Search for files and directories.
sort: Sort lines of text files.
uniq: Display or filter duplicate lines in a file.

File Compression and Archiving:

tar: Create or extract tar archives.
- tar -cvf archive.tar files: Create a tar archive.
- tar -xvf archive.tar: Extract files from a tar archive.
gzip or gunzip: Compress or decompress files.
- gzip file: Compress a file (creates .gz file).
- gunzip file.gz: Decompress a compressed file.

Disk Usage:

df: Display disk space usage.
du: Display file and directory space usage.
- du -h: Human-readable sizes.
- du -sh directory: Summarize directory size.

Other:

ln: Create symbolic or hard links.
file: Determine file type.
mount and umount: Mount and unmount filesystems.

Managing Processes:

ps: Display information about currently running processes.
- ps aux: Display detailed information about all processes.
- ps -ef: Similar to ps aux, different syntax.
top: Display real-time system monitoring and process information.
htop: Interactive version of top with more features and controls.
pgrep: Search for processes by name.
- Example: pgrep firefox to find the process ID of the Firefox browser.
pkill: Terminate processes by name.
- Example: pkill firefox to terminate all Firefox processes.
kill: Send signals to processes (commonly used with process IDs).
- kill -9 PID: Forcefully terminate a process with the given process ID.
killall: Terminate processes by name.
- Example: killall chrome to terminate all Chrome browser processes.
nice and renice: Adjust process priority.
- nice -n 10 command: Run a command with a lower priority (higher niceness value).
- renice -n 5 -p PID: Change the priority of a running process.

Background and Foreground Execution:

&: Run a command in the background.
- Example: command & runs command in the background.
jobs: List background jobs.
fg: Bring a background job to the foreground.
bg: Resume a suspended background job.

Process Control:

Ctrl+C: Interrupt (terminate) the currently running foreground process.
Ctrl+Z: Suspend the currently running foreground process.
nohup: Run a command that keeps running even after the terminal is closed.
- Example: nohup command &.

System Monitoring and Logs:

uptime: Display system uptime and load average.
vmstat: Display virtual memory statistics.
dmesg: Display kernel ring buffer (boot messages).
sar: Collect and display system activity information.
iostat: Display I/O statistics.

Network Configuration:

ifconfig or ip addr: Display network interface information.
ifup interface_name: Bring a network interface up.
ifdown interface_name: Bring a network interface down.
ip link set interface_name up: Another way to bring an interface up.
ip link set interface_name down: Another way to bring an interface down.
ping host: Send ICMP echo request packets to a host.
traceroute host: Trace the route that packets take to reach a host.

Network Connectivity:

ping host: Check network connectivity to a host.
traceroute host: Display the path taken by packets to reach a host.
nslookup host: Perform DNS lookups to retrieve IP addresses.
dig host: Another tool to query DNS information.
host host: Display DNS information.

Networking and Transfers:

wget: Download files from the internet.
curl: Transfer data to/from servers.

Network Diagnostics:

netstat: Display network statistics (deprecated; use ss instead).
ss: Display socket statistics.
nmap host: Perform network scanning to discover open ports and services.
arp: Display and manipulate the ARP cache.
iftop: Display bandwidth usage on an interface.
iftop -i interface_name: Monitor bandwidth of a specific interface.

Firewall and Security:

ufw: Uncomplicated Firewall management tool.
iptables: Powerful tool for configuring firewall rules.

Package Management:

Debian-based Distributions (e.g., Ubuntu):

apt-get update: Update the package list.
apt-get upgrade: Upgrade installed packages.
apt-get install package_name: Install a package.
apt-get remove package_name: Remove a package (keeps configuration files).
apt-get purge package_name: Completely remove a package (including configuration files).
apt-cache search keyword: Search for packages.
apt-cache show package_name: Display package information.
dpkg -i package.deb: Install a package from a .deb file.
dpkg -r package_name: Remove a package.
dpkg -l: List all installed packages.

Red Hat-based Distributions (e.g., CentOS):

yum update: Update installed packages.
yum install package_name: Install a package.
yum remove package_name: Remove a package.
yum search keyword: Search for packages.
yum info package_name: Display package information.
rpm -ivh package.rpm: Install a package from an .rpm file.
rpm -e package_name: Remove a package.
rpm -qa: List all installed packages.

Common for Both:

apt (Ubuntu) / yum (CentOS): Package managers to manage software.
snap: Package manager for installing and managing snap packages.
dnf: Modern package manager replacing yum in newer Fedora distributions.

Git and GitHub Cheat Sheet: Key Operations

Cloning a Repository:

git clone <repository_url>: Clone a remote repository to your local machine.

Basic Workflow:

Checking Status:
- git status: Check the status of your working directory and staged changes.
Adding Changes:
- git add <file>: Stage a specific file for commit.
- git add . or git add -A: Stage all changes for commit.
Committing Changes:
- git commit -m "Your commit message": Commit staged changes with a message.
Pushing Changes:
- git push origin <branch>: Push committed changes to a remote branch.

Branching and Merging:

Creating and Switching Branches:
- git branch: List all branches.
- git branch <new_branch>: Create a new branch.
- git checkout <branch>: Switch to an existing branch.
Merging Branches:
- git merge <branch_to_merge>: Merge changes from another branch into the current branch.

Pulling Changes:

git pull origin <branch>: Fetch and merge remote changes into your local branch.

Inspecting History:

git log: Display commit history.
git log --oneline: Display compact commit history.
git diff: Show differences between working directory and staging area.
git diff --staged: Show differences between staging area and last commit.

Remote Repositories:

git remote -v: List remote repositories.
git remote add <name> <repository_url>: Add a new remote repository.
git remote remove <name>: Remove a remote repository.
git push origin -d <branch-name> : Delete remote branch

Undoing Changes:

git reset <file>: Unstage changes from a file.
git checkout -- <file>: Discard changes in a file.
git revert <commit>: Create a new commit that undoes changes of a previous commit.

Resetting Commits:

git reset --soft <commit>: Move the branch pointer to a specific commit, keeping changes staged.
git reset --mixed <commit> (default behavior): Move the branch pointer and unstage changes, preserving changes in working directory.
git reset --hard <commit>: Move the branch pointer, unstage changes, and discard changes in working directory.

Ignoring Files:

Create a .gitignore file in the repository to list files and patterns to be ignored.

Renaming and Deleting:

git mv <old_file_name> <new_file_name>: Rename a file.
git rm <file>: Delete a file.

Remote Collaboration:

git clone <repository_url>: Clone a remote repository.
git fetch: Fetch changes from a remote repository.
git pull origin <branch>: Fetch and merge remote changes.
git push origin <branch>: Push changes to a remote branch.

Removing Untracked Files:

git clean -n: List untracked files that will be removed.
git clean -f: Remove untracked files from the working directory.

Stashing Changes:

git stash: Stash your changes (both staged and unstaged).
git stash save "message": Stash changes with a descriptive message.

Listing Stashes:

git stash list: List all stashes with their IDs and messages.

Applying Stashes:

git stash apply: Apply the most recent stash and keep it in the stash list.
git stash apply stash@{n}: Apply a specific stash by its index.

Popping Stashes:

git stash pop: Apply and remove the most recent stash.
git stash pop stash@{n}: Apply and remove a specific stash by its index.

Dropping Stashes:

git stash drop stash@{n}: Remove a specific stash by its index.
git stash clear: Remove all stashes.

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