Windows & Linux · Linux Command-Line

Linux Command-Line (Bash Shell)

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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

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

1) Navigating & Managing Directories

Commands

  • pwd — print current directory path
  • cd — change directories
  • mkdir / rmdir — create or remove (empty) directory
  • ls — list directory contents
pwd
cd /Documents
mkdir new_folder
rmdir new_folder
ls -la
cd example
Changing directories with cd.
mkdir example
Creating a directory with mkdir.
rmdir example
Removing an empty directory.

2) File Creation & Editing

Commands

  • touch — create or update timestamp
  • file — identify file type
  • nano — beginner-friendly editor
  • vi/vim — powerful modal editor
touch new_file.txt
file new_file.txt
nano new_file.txt
vi new_file.txt
touch and file usage
touch and file.
nano editor
Editing with nano.
vi editor
Editing with vi/vim.

3) Viewing & Searching File Content

Commands

  • cat — print file contents
  • ls -l — long listing (perms, owner, size, date)
  • tree — directory tree view
  • grep — pattern search
  • head / tail — first/last lines
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 output
cat a file.
ls -l
Long listing with ls -l.
tree output
Directory tree.
grep results
Searching with grep.
head and tail
head & tail.

4) Archiving & Locating Files

Commands

  • tar — create/extract archives
  • locate — indexed filename search
  • find — real-time search by name/size/time/etc.
tar -cvf archive.tar /home/user/documents
locate filename.txt
find /home -name "filename.txt"
tar usage
Creating an archive with tar.
find results
Finding files with find.

5) Users & Permissions

Commands

  • whoami — print current user
  • sudo — run command with elevated privileges
  • chmod — change permissions
  • chown — change owner/group
  • useradd / passwd / userdel — manage accounts
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 output
whoami output.
useradd and chown
Add user and change ownership.
userdel
Delete a user.

6) System Monitoring & Maintenance

Commands

  • df -h — filesystem space (human-readable)
  • du -sh — directory size summary
  • top / htop — live process viewers
  • uname -a — kernel/system info
df -h
du -sh /home/user
top
htop
uname -a
df output
df -h usage.
du output
du -sh usage.
top
top view.
top alt screen
Alternative top screen.
htop
htop overview.
htop details
More htop details.
uname
uname -a output.

7) Package Management

Commands

  • apt — Debian/Ubuntu package tool
  • dnf — Fedora/RHEL package tool
  • dpkg — low-level .deb installer
sudo apt install nano
sudo dnf update
sudo dpkg -i package.deb
apt update
apt update.
apt install
apt install.
dnf usage
dnf on Fedora/RHEL.
dpkg -i
dpkg -i to install a .deb.

8) Services & Processes

Commands

  • systemctl — control system services (start/stop/enable/status)
  • kill — send signals to processes by PID
sudo systemctl restart ssh
kill -9 <PID>
service status
Service status via systemctl.
systemctl usage
Managing services.
kill command
Killing a process.

9) System Operations

Commands

  • shutdown — safely power off
  • reboot — restart the system
sudo shutdown now
sudo reboot
shutdown command
Shutdown example.
reboot command
Reboot example.

10) Networking & Data Retrieval

Commands

  • wget — non-interactive downloader (HTTP/HTTPS/FTP)
  • curl — flexible client for transfers, APIs, tests
wget http://example.com/file.zip
curl http://example.com/file.zip -o file.zip
wget example
Downloading with wget.
curl example
Downloading with curl.

11) Utilities & Time

Commands

  • history — list your recent commands
  • echo — print text/variables
  • cal — calendar
  • time — measure a command's runtime
  • date — current date/time
history
echo "Hello World"
cal
time ls -la
date
history output
history listing.
history more
More history.
echo output
echo example.
calendar and date
cal and date.

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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