Master Essential Linux Commands: A Complete Cheat Sheet for System Operations

Linux Command Cheat Sheet

Table of Contents

Preface

1. cd command

2. pwd command

3. ls command

4. cp command

5. mv command

6. rm command

7. cat command

8. find command

9. chmod command

10. chown command

11. chgrp command

12. grep command

13. paste command

14. sort command

15. comm command

16. tar command

17. jps command

18. kill command

19. killall command

20. System shutdown/reboot

21. top command

22. touch command

23. mkdir command

24. ps command

25. ping command

26. ifconfig command

27. Redirection operators

28. Pipe operator

29. cut command

Other useful commands

Summary

Preface

Linux common commands are tools widely used in the Linux operating system to manage files, directories, processes, network communication, software installation, and more. Mastering these commands improves efficiency when working with Linux.

1. cd command

The cd command changes the current working directory to the specified path.

cd ..        # Return to parent directory
cd ../..    # Return two levels up
cd ~         # Go to the home directory
cd -         # Return to the previous directory

2. pwd command

The pwd command displays the full path of the current working directory.

3. ls command

The ls command lists files and directories in the specified location.

ls                # List files in current directory
ls -l (ll)       # Detailed list with permissions
ls -a            # Include hidden files
ls -R            # Recursively list subdirectories
ls [0-9]         # Show files containing numbers in their names

4. cp command

The cp command copies files or directories.

-a   # Preserve attributes
-p   # Preserve mode, ownership, timestamps (useful for backup)
-i   # Prompt before overwriting
-r   # Recursively copy directories
-u   # Copy only when source is newer than destination

5. mv command

The mv command moves or renames files or directories.

-f   # Force overwrite without prompting
-i   # Prompt before overwriting
-u   # Overwrite only if source is newer

6. rm command

The rm command deletes files or directories.

-f   # Ignore nonexistent files, never prompt
-i   # Prompt before each removal
-r   # Recursively delete directories

7. cat command

The cat command displays file contents and can concatenate files.

cat file1               # Show file from start
tac file1               # Show file in reverse order
cat -n file1            # Number lines
more file1              # Paginated view
head -n 2 file1         # First two lines
tail -n 2 file1         # Last two lines

8. find command

The find command searches for files and directories based on criteria.

find / -name file1                 # Search from root
find / -user user1                  # Files owned by user1
find /usr/bin -type f -atime +100  # Executables not accessed in 100 days
find /usr/bin -type f -mtime -10   # Files modified within last 10 days

9. chmod command

The chmod command changes file or directory permissions.

chmod ugo+rwx directory1   # Grant read/write/execute to all
chmod go-rwx directory1   # Remove permissions from group and others

10. chown command

The chown command changes file ownership.

chown user1 file1               # Change owner
chown -R user1 directory1       # Recursively change owner
chown user1:group1 file1        # Change owner and group

11. chgrp command

The chgrp command changes the group ownership of a file.

chgrp group1 file1

12. grep command

The grep command searches for patterns within files.

grep keyword file.txt               # Find lines containing keyword
grep ^Aug /var/log/messages        # Lines starting with "Aug"
grep [0-9] /var/log/messages       # Lines containing numbers

13. paste command

The paste command merges lines of files side by side.

paste file1 file2                # Merge two files
paste -d '+' file1 file2        # Use '+' as delimiter

14. sort command

The sort command orders lines of text.

sort file1                     # Sort file alphabetically
sort -r file1                  # Reverse order
sort -n file1                  # Numeric sort
sort -u file1                  # Unique lines only

15. comm command

The comm command compares two sorted files.

comm -1 file1 file2   # Lines only in file1
comm -2 file1 file2   # Lines only in file2
comm -3 file1 file2   # Lines common to both

16. tar command

The tar command creates and extracts archive files.

-c   # Create archive
-t   # List contents
-x   # Extract archive
-j   # Use bzip2 compression
-z   # Use gzip compression
-v   # Verbose output
-f filename   # Specify archive file
-C dir        # Change to directory before operation

16-1 Parameter Overview

-c : create archive
-t : list archive contents
-x : extract archive
-j : bzip2 compression
-z : gzip compression
-v : verbose
-f filename : archive name
-C dir : target directory

16-2 tar.bz2 format

tar -jcvf archive.tar.bz2 source   # Compress with bzip2
tar -jtvf archive.tar.bz2          # List contents
tar -jxvf archive.tar.bz2 -C /dest  # Extract

16-3 tar.gz format

tar -zcvf archive.tar.gz source   # Compress with gzip
tar -zxvf archive.tar.gz -C /dest # Extract

16-4 tar (no compression)

tar -cvf archive.tar source   # Create plain tar archive
tar -xvf archive.tar -C /dest # Extract

16-5 zip format

zip -r archive.zip source          # Create zip archive
unzip archive.zip                 # Extract zip archive

16-6 Other related commands

bzip2 file1      # Compress with bzip2
bunzip2 file1.bz2 # Decompress bzip2 file
gzip file1       # Compress with gzip
gunzip file1.gz   # Decompress gzip file
rar a file1.rar source   # Create rar archive
rar x file1.rar          # Extract rar archive

17. jps command

The jps tool lists Java processes.

jps -l   # Full class name
jps -m   # Show main class and arguments

18. kill command

The kill command sends signals to processes.

kill [signal] PID   # Send signal (default SIGTERM)
SIGKILL   # Force termination
SIGTERM   # Graceful termination

19. killall command

The killall command terminates processes by name.

killall process_name

20. System shutdown/reboot

shutdown -h now          # Halt now
shutdown -r now          # Reboot now
reboot                   # Reboot
logout                   # Log out

21. top command

The top command displays real‑time system resource usage.

22. touch command

The touch command creates empty files or updates timestamps.

23. mkdir command

The mkdir command creates new directories.

24. ps command

The ps command lists running processes.

25. ping command

The ping command tests network connectivity.

26. ifconfig command

The ifconfig command shows network interface configuration.

27. Redirection operators

Use > to redirect output to a file, >> to append, and < to use a file as input.

28. Pipe operator

The | symbol passes the output of one command as input to another, enabling command chaining.

29. cut command

The cut command extracts sections from each line of input.

cut -c 1,3 file.txt               # Characters 1 and 3
cut -d ':' -f 2,4 file.txt        # Fields 2 and 4 using ':' as delimiter
cut -c 1,3 --complement file.txt # All but characters 1 and 3

Other useful commands

wc -l file # Count lines in a file

more file # View file page by page

sudo -i # Switch to root shell without repeated password prompts

Summary

Common options such as -a (all), -f (force), -i (interactive), and -r (recursive) apply across many commands, providing flexible control over file and process operations.