50 Linux Terminal Commands
1. whoami
Description: Displays the username of the current user.
whoami
Example:
Running whoami will display the username currently logged into the terminal. This can be useful to confirm that you have the proper permissions or that you are in the correct user session.
Output Example:
username
2. man
Description: Displays the manual for a command, which includes the description, options, and examples for using the command.
man ls
Example:
To learn about all the options available for the ls command, use man ls. The manual pages (or "man pages") are an essential resource for understanding the functionality of Linux commands.
Tip: Use the arrow keys to navigate, and press q to quit the manual.
3. clear
Description: Clears the terminal screen for a cleaner workspace.
clear
Example:
After running many commands, the terminal can become cluttered with outputs. Running clear will wipe the screen and make it easier to work with subsequent commands.
4. Intro to Options
Description: Many commands can be extended with options to provide more specific functionality.
List files with options (ls -l)
ls -l
Example:
Using -l with ls will list files in a detailed format including permissions, number of links, owner, group, size, and the last modification date of each file or directory.
Output Example:
drwxr-xr-x 5 user group 4096 Oct 7 10:00 Documents
-rw-r--r-- 1 user group 123 Oct 7 11:00 file.txt
5. pwd
Description: Prints the full path of the current working directory.
pwd
Example:
Running pwd helps you confirm where you are within the filesystem hierarchy, which is particularly helpful when navigating deeply nested directories.
Output Example:
/home/username/Documents
6. ls
Description: Lists the contents of a directory.
ls
Options:
-a- Includes hidden files (files beginning with.).-l- Shows detailed information about each file.-h- Makes file sizes human-readable (e.g.,1K,234M).
Example: To list all files, including hidden ones, in the home directory:
ls -a ~
7. cd
Description: Changes the current directory.
cd Documents
Options:
cd ~- Changes to the home directory.cd ..- Moves up one directory level.cd /path/to/directory- Changes to a specific directory.
Example: Navigate up one level from the current directory:
cd ..
8. mkdir
Description: Creates a new directory.
mkdir new_folder
Options:
-p- Creates parent directories if they do not exist.
Example: Create multiple nested directories in one go:
mkdir -p projects/2024/webdev
9. touch
Description: Creates an empty file or updates the timestamp of an existing file.
touch file.txt
Example: To create multiple files at once:
touch file1.txt file2.txt file3.txt
10. rmdir
Description: Removes an empty directory.
rmdir old_folder
Note:
rmdir only works on empty directories. To remove non-empty directories, use rm -r.
Example:
Attempt to remove a directory called backup, but only if it's empty:
rmdir backup
11. rm
Description: Removes files or directories.
rm file.txt
Options:
-r- Recursively remove a directory and its contents.-f- Force removal without prompting.
Example: Remove a directory and all its contents without confirmation:
rm -rf unwanted_folder
12. open (macOS only)
Description: Opens a file or directory with the default application.
open file.txt
Example: To open the current directory in Finder:
open .
13. mv
Description: Moves or renames files and directories.
mv old_name.txt new_name.txt
Options:
- Moving a file to a different directory:
mv file.txt /path/to/destination/
Example: Rename a directory:
mv old_folder_name new_folder_name
14. cp
Description: Copies files or directories.
cp source.txt destination.txt
Options:
-r- Copy directories recursively.-i- Prompt before overwriting existing files.
Example: Copy a folder and its contents to another location:
cp -r folder/ backup/
15. head
Description: Displays the first 10 lines of a file by default.
head file.txt
Options:
-n- Specify the number of lines to display.
Example: Show the first 5 lines of a file:
head -n 5 file.txt
16. tail
Description: Displays the last 10 lines of a file by default.
tail file.txt
Options:
-n- Specify the number of lines to display.-f- Follow the file as new content is added (useful for log files).
Example: Monitor a log file in real-time:
tail -f /var/log/syslog
17. date
Description: Displays the current date and time.
date
Example: Format the date in a custom way:
date "+%Y-%m-%d %H:%M:%S"
18. Redirecting Standard Output
Description: Redirects the output of a command to a file.
ls > file_list.txt
Options:
>- Overwrite the file with the output.>>- Append the output to the file.
Example:
Append the list of current files to file_list.txt:
ls >> file_list.txt
19. cat
Description: Concatenates and displays the content of files.
cat file.txt
Options:
> newfile- Redirect output to create a new file.
Example: Combine two files into a new file:
cat file1.txt file2.txt > combined.txt
20. less
Description: Allows you to view a file one page at a time, providing better navigation than cat.
less file.txt
Controls:
- Use
Spaceto scroll down,bto scroll up, andqto quit.
Example:
View a large log file with less to navigate efficiently.
21. echo
Description: Prints a message or value to the terminal.
echo "Hello, World!"
Example: Display the value of an environment variable:
echo $HOME
22. wc
Description: Counts lines, words, and characters in a file.
wc file.txt
Options:
-l- Count lines.-w- Count words.-c- Count characters.
Example: Count the number of lines in a file:
wc -l file.txt
23. Piping (|)
Description: Combines two or more commands, using the output of one command as input to another.
ls | wc -l
Example:
Find the number of .txt files in the current directory:
ls *.txt | wc -l
24. sort
Description: Sorts the lines of a file or input.
sort file.txt
Options:
-r- Reverse the sort order.-n- Sort numerically.
Example: Sort a file in descending order:
sort -r file.txt
25. uniq
Description: Filters out repeated lines in a file, typically used in combination with sort.
uniq duplicate_lines.txt
Options:
-c- Prefix each line with the count of occurrences.
Example: Count the number of unique lines in a sorted file:
sort file.txt | uniq -c
26. Expansions
Description: Uses wildcard characters to perform operations on multiple files.
echo *.txt
Example:
Delete all .tmp files in the current directory:
rm *.tmp
27. diff
Description: Compares two files line by line.
diff file1.txt file2.txt
Options:
-u- Unified output format (useful for patching).
Example: Show the differences between two configuration files:
diff -u config_old.txt config_new.txt
28. find
Description: Searches for files and directories based on criteria.
find . -name "example.txt"
Options:
-type d- Search for directories.-type f- Search for files.
Example:
Find all .log files modified in the last 7 days:
find /var/log -name "*.log" -mtime -7
29. grep
Description: Searches for a pattern within files.
grep "search_term" file.txt
Options:
-i- Ignore case.-r- Search recursively in directories.-n- Show line numbers.
Example: Find all occurrences of "error" in log files:
grep -i "error" /var/log/*.log
30. du
Description: Estimates file space usage of a directory.
du -h
Options:
-s- Summarize total.
Example:
Display the total size of the Documents directory:
du -sh Documents/
31. df
Description: Displays file system disk space usage.
df -h
Options:
-h- Human-readable output.-T- Show filesystem type.
Example: View available disk space on all mounted filesystems:
df -Th
32. history
Description: Shows a list of previously executed commands.
history
Options:
!<number>- Run the command associated with the specified history number.
Example: Run the 50th command in the history list:
!50
33. ps
Description: Displays information about running processes.
ps
Options:
-e- Show all processes.-f- Full format listing.
Example: List all processes in a detailed format:
ps -ef
34. top
Description: Displays real-time information about system processes, including CPU and memory usage.
top
Note:
Press q to quit top.
Example:
To sort processes by memory usage, press M while in top.
35. kill
Description: Kills a process by its Process ID (PID).
kill 1234
Example: To kill a process forcefully:
kill -9 1234
36. killall
Description: Kills all processes by name.
killall firefox
Options:
-9- Force kill.
Example: Forcefully terminate all instances of Chrome:
killall -9 chrome
37. jobs, bg, and fg
Description: Manages background jobs.
jobs
bg %1
fg %1
Example: List current jobs:
jobs
Move the first job to the background:
bg %1
Bring the first job back to the foreground:
fg %1
38. gzip
Description: Compresses files using the gzip format.
gzip file.txt
Options:
-d- Decompress a.gzfile.
Example: Compress multiple text files:
gzip file1.txt file2.txt
39. gunzip
Description: Decompresses .gz files.
gunzip file.txt.gz
Example:
To decompress multiple .gz files:
gunzip *.gz
40. tar
Description: Creates or extracts tar archives.
Create an archive:
tar -cvf archive.tar directory/
Extract an archive:
tar -xvf archive.tar
Options:
-z- Compress or decompress using gzip.
Example:
Create a compressed .tar.gz archive:
tar -czvf archive.tar.gz directory/
41. nano
Description: Opens the nano text editor to edit files.
nano file.txt
Note:
Use CTRL + X to exit, Y to save changes, or N to discard changes.
Example: To edit a configuration file:
sudo nano /etc/hosts
42. alias
Description: Creates an alias for a command.
alias ll='ls -la'
Example:
To make rm always prompt before deletion:
alias rm='rm -i'
43. xargs
Description: Constructs arguments for a command using input from another command.
cat files.txt | xargs rm
Example:
Find all .txt files and remove them:
find . -name "*.txt" | xargs rm
44. ln
Description: Creates links between files.
Symbolic link:
ln -s /path/to/original /path/to/link
Example: Create a symbolic link for a configuration file:
ln -s /etc/nginx/nginx.conf ~/nginx.conf
45. who
Description: Shows who is currently logged in to the system.
who
Example: Check who else is logged into the system alongside you:
who
46. su
Description: Switches to another user account.
su username
Example: Switch to the root user:
su -
47. sudo
Description: Executes a command as the superuser or another user.
sudo apt-get update
Note:
Requires the current user to be in the sudoers file.
Example: Edit a protected file:
sudo nano /etc/fstab
48. passwd
Description: Changes the password for a user.
passwd
Example: Change another user's password (requires superuser privileges):
sudo passwd username
49. chown
Description: Changes file or directory ownership.
chown user:group file.txt
Options:
-R- Recursively change ownership for a directory and its contents.
Example: Change the owner of all files in a directory:
chown -R user:group /path/to/directory
50. chmod
Description: Changes file or directory permissions.
chmod 755 script.sh
Options:
u- User permissions.g- Group permissions.o- Others' permissions.
Example: Make a file readable and writable only by the owner:
chmod 600 private.txt