Linux & Bash Reference

Basic navigation

pwd

Prints the current working directory.

ls

Lists files and directories.

ls -la

Lists all files (including hidden) with details.

cd directory

Changes directory.

cd ..

Moves up one directory.

cd ~

Goes to home directory.

File and directory management

touch file.txt

Creates an empty file.

mkdir folder

Creates a directory.

mkdir -p parent/child

Creates nested directories.

cp file.txt copy.txt

Copies a file.

cp -r dir1 dir2

Copies a directory recursively.

mv old.txt new.txt

Moves or renames files.

rm file.txt

Deletes a file.

rm -r folder

Deletes a directory recursively.

rm -rf folder

DANGER: Force deletes without confirmation.

Viewing file content

cat file.txt

Prints file content.

less file.txt

Views file content page by page.

head file.txt

Shows the first lines of a file.

tail file.txt

Shows the last lines of a file.

tail -f logfile.log

Follows a file in real time (logs).

Searching and finding

grep "text" file.txt

Searches for text inside a file.

grep -r "text" folder

Recursive search in directories.

find . -name "file.txt"

Finds files by name.

find . -type f

Finds all files.

Permissions and ownership

ls -l

Shows permissions and ownership.

chmod +x script.sh

Makes a file executable.

chmod 755 file

Sets permissions using numeric mode.

chown user:group file

Changes file owner and group.

Processes and system

ps

Shows running processes.

ps aux

Lists all processes.

top

Interactive process viewer.

htop

Improved process viewer (if installed).

kill PID

Stops a process by ID.

kill -9 PID

Force kills a process.

Disk and system info

df -h

Shows disk usage.

du -sh folder

Shows folder size.

free -h

Displays memory usage.

uname -a

Shows system information.

Networking

ip a

Shows network interfaces.

ping google.com

Tests network connectivity.

curl https://example.com

Requests a URL from terminal.

wget https://example.com/file.zip

Downloads a file.

Redirection and pipes

command > file.txt

Redirects output to a file (overwrite).

command >> file.txt

Appends output to a file.

command1 | command2

Pipes output of one command into another.

grep "error" log.txt | less

Example of piping commands.

Compression and archives

tar -czvf archive.tar.gz folder

Creates a compressed archive.

tar -xzvf archive.tar.gz

Extracts a compressed archive.

zip -r file.zip folder

Creates a zip archive.

unzip file.zip

Extracts a zip archive.

Environment and shell

echo $PATH

Shows PATH environment variable.

env

Lists environment variables.

which node

Shows the path of a command.

history

Shows command history.

clear

Clears the terminal screen.

Recommended daily workflow

pwd
ls
cd project
ls -la
grep "TODO" .
tail -f logs/app.log

Common commands used during development and debugging.

Best practices

• Double-check before using rm -rf.
• Use less instead of cat for large files.
• Prefer pipes over temporary files.
• Learn to read permissions and ownership.