Windows & Linux · Linux Command-Line

Linux Command-Line (Bash Shell)

The terminal + Bash give precise control over files, processes, networking, and more. Below are core commands with examples and screenshots.

Commands you type are small programs (e.g., /bin/ls, /bin/cp). The terminal sends your input to the shell, usually Bash (Bourne Again Shell), which parses and executes them.

How a Command Runs

You type a command (e.g., ls -l).
The terminal forwards it to the shell (Bash).
Bash parses the command (syntax, expansions, variables).
It resolves the executable (e.g., /bin/ls) and runs it.
Output is printed back to the terminal.

1) Navigating & Managing Directories

pwd
cd /Documents
mkdir new_folder
rmdir new_folder
ls -la

pwd — print current directory path
cd — change directories
mkdir / rmdir — create or remove (empty) directory
ls — list directory contents

cd example — Changing directories with `cd`.

mkdir example — Creating a directory with `mkdir`.

rmdir example — Removing an empty directory.

2) File Creation & Editing

touch new_file.txt
file new_file.txt
nano new_file.txt
vi new_file.txt

touch — create or update timestamp
file — identify file type
nano — beginner-friendly editor
vi/vim — powerful modal editor

touch and file usage — `touch` and `file`.

3) Viewing & Searching File Content

cat new_file.txt
ls -l /home/user
tree
grep "search_term" new_file.txt
head -n 5 new_file.txt
tail -n 5 new_file.txt

cat — print file contents
ls -l — long listing (perms, owner, size, date)
tree — directory tree view
grep — pattern search
head/tail — first/last lines

4) Archiving & Locating Files

tar -cvf archive.tar /home/user/documents
locate filename.txt
find /home -name "filename.txt"

tar — create/extract archives
locate — indexed filename search
find — real-time search by name/size/time/etc.

tar usage — Creating an archive with `tar`.

find results — Finding files with `find`.

5) Users & Permissions

whoami
sudo apt update
chmod 755 new_file.txt
chown user:user new_file.txt
sudo useradd newuser
sudo passwd newuser
sudo userdel newuser

whoami — print current user
sudo — run command with elevated privileges
chmod — change permissions
chown — change owner/group
useradd / passwd / userdel — manage accounts

useradd and chown — Add user and change ownership.

6) System Monitoring & Maintenance

df -h
du -sh /home/user
top
htop
uname -a

df -h — filesystem space (human-readable)
du -sh — directory size summary
top / htop — live process viewers
uname -a — kernel/system info

top alt screen — Alternative `top` screen.

7) Package Management

sudo apt install nano
sudo dnf update
sudo dpkg -i package.deb

apt — Debian/Ubuntu package tool
dnf — Fedora/RHEL package tool
dpkg — low-level .deb installer

8) Services & Processes

sudo systemctl restart ssh
kill -9 <PID>

systemctl — control system services (start/stop/enable/status)
kill — send signals to processes by PID

service status — Service status via `systemctl`.

9) System Operations

sudo shutdown now
sudo reboot

shutdown — safely power off
reboot — restart the system

10) Networking & Data Retrieval

wget http://example.com/file.zip
curl http://example.com/file.zip -o file.zip

wget — non-interactive downloader (HTTP/HTTPS/FTP)
curl — flexible client for transfers, APIs, tests

11) Utilities & Time

history
echo "Hello World"
cal
time ls -la
date

history — list your recent commands
echo — print text/variables
cal — calendar
time — measure a command's runtime
date — current date/time

Conclusion

The CLI isn't magic — it's a shell interpreting your input and running small programs. Mastering these commands builds a strong foundation for administration, scripting, and troubleshooting. Explore man <command> for deeper options.

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