The terminal (also called command line, shell, or console) is a text-based interface for interacting with your Ubuntu system. While Ubuntu has a graphical interface, the terminal provides powerful tools for system administration, development, and automation.
Ctrl + Alt + TSuper key, type “terminal”username@hostname:~/current/directory$ command
│ │ │ │
│ │ │ └── Command to execute
│ │ └── Current working directory
│ └── Computer name
└── Current user
Example:
john@ubuntu-desktop:~/Documents$ ls
# Print current directory
pwd
# List directory contents
ls
# List with detailed information
ls -l
# List including hidden files
ls -la
# List with human-readable file sizes
ls -lh
# Change directory
cd /path/to/directory
# Go to home directory
cd ~
# or simply
cd
# Go up one directory
cd ..
# Go to previous directory
cd -
# Go to root directory
cd /
# Navigate to your home directory
cd ~
# Navigate to Documents folder
cd Documents
# Go back to previous directory
cd ..
# Navigate using absolute path
cd /usr/local/bin
# Navigate using relative path
cd ../Downloads
# Quick navigation to common directories
cd ~/Desktop # Desktop folder
cd ~/Downloads # Downloads folder
cd ~/Pictures # Pictures folder
# Create an empty file
touch filename.txt
# Create multiple files
touch file1.txt file2.txt file3.txt
# Create a directory
mkdir directory_name
# Create multiple directories
mkdir dir1 dir2 dir3
# Create nested directories
mkdir -p parent/child/grandchild
# Create directory with specific permissions
mkdir -m 755 secure_directory
# Copy a file
cp source_file.txt destination_file.txt
# Copy file to another directory
cp file.txt ~/Documents/
# Copy multiple files
cp file1.txt file2.txt ~/Documents/
# Copy directory and its contents
cp -r source_directory destination_directory
# Copy with verbose output
cp -v file.txt ~/Documents/
# Copy preserving attributes
cp -p file.txt backup_file.txt
# Move/rename a file
mv old_name.txt new_name.txt
# Move file to another directory
mv file.txt ~/Documents/
# Move multiple files
mv file1.txt file2.txt ~/Documents/
# Move directory
mv old_directory new_directory
# Move with confirmation
mv -i file.txt ~/Documents/
# Remove a file
rm filename.txt
# Remove multiple files
rm file1.txt file2.txt file3.txt
# Remove with confirmation
rm -i filename.txt
# Remove directory and contents
rm -r directory_name
# Force remove (be careful!)
rm -f filename.txt
# Force remove directory and contents (DANGEROUS!)
rm -rf directory_name
# Remove empty directory
rmdir empty_directory
# Display entire file
cat filename.txt
# Display file with line numbers
cat -n filename.txt
# View file page by page
less filename.txt
# Navigation in less: Space (next page), b (previous page), q (quit)
# Alternative pager
more filename.txt
# Display first 10 lines
head filename.txt
# Display first N lines
head -n 20 filename.txt
# Display last 10 lines
tail filename.txt
# Display last N lines
tail -n 15 filename.txt
# Follow file changes (useful for logs)
tail -f /var/log/syslog
# Create file with content using echo
echo "Hello, World!" > hello.txt
# Append content to file
echo "Second line" >> hello.txt
# Create file using cat (Ctrl+D to save)
cat > newfile.txt
This is the content
Press Ctrl+D to save
# Edit file with nano (beginner-friendly)
nano filename.txt
# Edit file with vim (advanced)
vim filename.txt
# Edit file with gedit (GUI editor)
gedit filename.txt
# Search for pattern in file
grep "pattern" filename.txt
# Search case-insensitively
grep -i "pattern" filename.txt
# Search recursively in directories
grep -r "pattern" /path/to/directory
# Search and show line numbers
grep -n "pattern" filename.txt
# Search for whole words only
grep -w "word" filename.txt
# Search for multiple patterns
grep -E "pattern1|pattern2" filename.txt
# Count matching lines
grep -c "pattern" filename.txt
-rwxrwxrwx
│││││││││
│││└┬┘└┬┘
│││ │ └── Others permissions (read, write, execute)
│││ └──── Group permissions (read, write, execute)
│└┬────── Owner permissions (read, write, execute)
└─────── File type (- for file, d for directory)
| Permission | Symbol | Numeric |
|---|---|---|
| Read | r | 4 |
| Write | w | 2 |
| Execute | x | 1 |
Common combinations:
755 = rwxr-xr-x (Owner: read+write+execute, Group: read+execute, Others: read+execute)644 = rw-r–r– (Owner: read+write, Group: read, Others: read)600 = rw——- (Owner: read+write, Group: none, Others: none)# Change permissions using symbolic notation
chmod u+x filename.txt # Add execute for owner
chmod g-w filename.txt # Remove write for group
chmod o+r filename.txt # Add read for others
chmod a+x filename.txt # Add execute for all
# Change permissions using numeric notation
chmod 755 filename.txt # rwxr-xr-x
chmod 644 filename.txt # rw-r--r--
chmod 600 filename.txt # rw-------
# Change permissions recursively
chmod -R 755 directory/
# Change file owner
sudo chown username filename.txt
# Change file owner and group
sudo chown username:groupname filename.txt
# Change ownership recursively
sudo chown -R username:groupname directory/
# Change only group
sudo chgrp groupname filename.txt
# Display system information
uname -a
# Display operating system information
lsb_release -a
# Show current user
whoami
# Show current user ID
id
# Display system uptime
uptime
# Show system date and time
date
# Show calendar
cal
# Show users currently logged in
who
# Show what users are doing
w
# Display running processes
ps aux
# Interactive process viewer
top
# Better process viewer (if installed)
htop
# Display memory usage
free -h
# Display disk usage
df -h
# Display directory size
du -h directory/
# Display directory size summary
du -sh directory/
# Monitor system resources
iostat
vmstat
# List PCI devices
lspci
# List USB devices
lsusb
# List block devices (storage)
lsblk
# CPU information
lscpu
# Memory information
cat /proc/meminfo
# Hardware information
sudo lshw
# Hardware summary
sudo lshw -short
# Update package lists
sudo apt update
# Upgrade installed packages
sudo apt upgrade
# Full system upgrade
sudo apt full-upgrade
# Install package
sudo apt install package-name
# Install multiple packages
sudo apt install package1 package2 package3
# Remove package
sudo apt remove package-name
# Remove package and configuration files
sudo apt purge package-name
# Remove orphaned packages
sudo apt autoremove
# Search for packages
apt search keyword
# Show package information
apt show package-name
# List installed packages
apt list --installed
# List upgradable packages
apt list --upgradable
# Check if package is installed
dpkg -l | grep package-name
# List files installed by package
dpkg -L package-name
# Find which package provides a file
dpkg -S /path/to/file
# Show package dependencies
apt depends package-name
# Show reverse dependencies
apt rdepends package-name
# Display network interfaces
ip addr show
# or
ifconfig
# Display routing table
ip route show
# or
route -n
# Test network connectivity
ping google.com
# Test specific port connectivity
telnet hostname port
# Download files from internet
wget http://example.com/file.zip
# Alternative download tool
curl -O http://example.com/file.zip
# Display network connections
netstat -tuln
# Show listening ports
ss -tuln
# Bring interface up
sudo ip link set interface_name up
# Bring interface down
sudo ip link set interface_name down
# Restart network service
sudo systemctl restart networking
# Flush DNS cache
sudo systemd-resolve --flush-caches
# Show DNS configuration
systemd-resolve --status
# Start process in background
command &
# List background jobs
jobs
# Bring background job to foreground
fg %1
# Send job to background
bg %1
# Kill process by PID
kill PID
# Kill process forcefully
kill -9 PID
# Kill process by name
killall process-name
# Kill all processes matching pattern
pkill pattern
# Check service status
sudo systemctl status service-name
# Start service
sudo systemctl start service-name
# Stop service
sudo systemctl stop service-name
# Restart service
sudo systemctl restart service-name
# Enable service at boot
sudo systemctl enable service-name
# Disable service at boot
sudo systemctl disable service-name
# List all services
systemctl list-units --type=service
# List failed services
systemctl --failed
# Create tar archive
tar -cvf archive.tar files/
# Create compressed tar archive (gzip)
tar -czvf archive.tar.gz files/
# Create compressed tar archive (bzip2)
tar -cjvf archive.tar.bz2 files/
# Create zip archive
zip -r archive.zip files/
# Extract tar archive
tar -xvf archive.tar
# Extract compressed tar archive (gzip)
tar -xzvf archive.tar.gz
# Extract compressed tar archive (bzip2)
tar -xjvf archive.tar.bz2
# Extract to specific directory
tar -xzvf archive.tar.gz -C /path/to/directory
# Extract zip archive
unzip archive.zip
# List archive contents without extracting
tar -tzvf archive.tar.gz
zip -l archive.zip
# Sort lines in file
sort filename.txt
# Sort and remove duplicates
sort -u filename.txt
# Remove duplicate lines
uniq filename.txt
# Count lines, words, characters
wc filename.txt
# Count only lines
wc -l filename.txt
# Cut specific columns
cut -d',' -f1,3 file.csv
# Find and replace text
sed 's/old/new/g' filename.txt
# Replace text in-place
sed -i 's/old/new/g' filename.txt
# Process text with awk
awk '{print $1}' filename.txt
# Print specific columns
awk '{print $1, $3}' filename.txt
# Filter and process
awk '$3 > 100 {print $1, $3}' data.txt
# Compare files
diff file1.txt file2.txt
# Compare directories
diff -r dir1/ dir2/
# Redirect output to file
command > output.txt
# Append output to file
command >> output.txt
# Redirect error to file
command 2> error.txt
# Redirect both output and error
command > output.txt 2>&1
# Redirect to null (discard)
command > /dev/null
# Pipe output to another command
command1 | command2
# Pipe with tee (output to file and screen)
command | tee output.txt
# Save directory listing to file
ls -la > directory_listing.txt
# Search and save results
grep "error" /var/log/syslog > errors.txt
# Count files in directory
ls | wc -l
# Find largest files
ls -la | sort -k5 -nr | head -10
# Monitor log file with filter
tail -f /var/log/syslog | grep "error"
# Display all environment variables
env
# Display specific variable
echo $HOME
echo $PATH
echo $USER
# Set temporary variable
export MY_VAR="value"
# Add to PATH
export PATH=$PATH:/new/path
# Make permanent (add to ~/.bashrc)
echo 'export MY_VAR="value"' >> ~/.bashrc
source ~/.bashrc
| Variable | Description | Example |
|---|---|---|
$HOME |
User’s home directory | /home/username |
$PATH |
Executable search path | /usr/bin:/bin:/usr/local/bin |
$USER |
Current username | username |
$PWD |
Current working directory | /home/username/Documents |
$SHELL |
Current shell | /bin/bash |
# Show command history
history
# Show last N commands
history 10
# Search command history
history | grep "command"
# Execute command from history
!123 # Execute command number 123
!! # Execute last command
!string # Execute last command starting with 'string'
| Shortcut | Action |
|---|---|
Ctrl + C |
Cancel current command |
Ctrl + D |
Exit shell/logout |
Ctrl + Z |
Suspend current process |
Ctrl + L |
Clear screen |
Ctrl + A |
Move to beginning of line |
Ctrl + E |
Move to end of line |
Ctrl + U |
Delete from cursor to beginning |
Ctrl + K |
Delete from cursor to end |
Ctrl + R |
Search command history |
Tab |
Auto-complete |
Tab Tab |
Show all possibilities |
# Show command manual
man command
# Show command help
command --help
# Show brief description
whatis command
# Search manual pages
apropos keyword
# Show command location
which command
# Show command type
type command
# Get info about command
info command
# Find and delete files older than 30 days
find /path -type f -mtime +30 -delete
# Show disk usage of current directory, sorted
du -h | sort -hr
# Find largest directories
du -h --max-depth=1 | sort -hr
# Monitor system load
watch -n 1 'uptime'
# Show network connections with process names
sudo netstat -tulpn
# Find processes using most memory
ps aux --sort=-%mem | head
# Find files containing text
find /path -type f -exec grep -l "text" {} \;
# Count files by extension
find . -type f | sed 's/.*\.//' | sort | uniq -c | sort -nr
# Use -i flag for confirmation
rm -i important_file.txt
cp -i source dest
# Type partial command and press Tab
cd Doc<Tab> # Expands to Documents/
# Test regex on small file before applying to large dataset
grep "pattern" small_file.txt
cp important_file.txt important_file.txt.backup
alias ll='ls -la'
alias la='ls -A'
alias l='ls -CF'
# Use output of one command in another
echo "Today is $(date)"
cd $(dirname $(which python))
# Execute second command only if first succeeds
make && make install
# Execute second command only if first fails
test -f file.txt || touch file.txt
After mastering basic terminal commands:
The terminal is a powerful tool that becomes more valuable as you learn to use it effectively. Start with basic commands and gradually build your skills:
| Skill Level | Focus Areas |
|---|---|
| Beginner | Navigation, file operations, basic text viewing |
| Intermediate | Permissions, process management, text processing |
| Advanced | Scripting, automation, system administration |
Remember: The terminal might seem intimidating at first, but with practice, it becomes an indispensable tool for efficient system management and development work.