Bash / Shell Command Reference

Navigation

Command	What it does	Example
cd	Change directory	cd /path/to/directory
pwd	Print working directory	pwd

Files & Directories

Command	What it does	Example
ls	List directory contents	ls
ls -la	List all files, including hidden ones	ls -la
mkdir	Create a directory	mkdir new_directory
mkdir -p	Create a directory and its parent directories	mkdir -p /path/to/new_directory
rmdir	Remove an empty directory	rmdir empty_directory

Viewing & Searching

Command	What it does	Example
cat	Display the contents of a file	cat file.txt
less	View a file page by page	less file.txt
head	Display the first few lines of a file	head file.txt
tail	Display the last few lines of a file	tail file.txt
tail -f	Follow the end of a file as it grows	tail -f log.txt
grep	Search for text in files	grep "search_term" file.txt
grep -r	Recursively search for text in files	grep -r "search_term" /path/to/directory
find	Find files and directories	find /path/to/search -name "filename"
wc	Count lines, words, and characters in files	wc file.txt

Permissions

Command	What it does	Example
chmod	Change file permissions	chmod 755 file.txt
chmod +x	Make a file executable	chmod +x script.sh
chown	Change file ownership	chown user:group file.txt
umask	Set default file permissions	umask 022

Processes

Command	What it does	Example
ps aux	List all running processes	ps aux
top	Display real-time process information	top
kill	Terminate a process	kill 1234
kill -9	Forcefully terminate a process	kill -9 1234
jobs	List background jobs	jobs
bg	Resume a background job	bg %1
fg	Resume a foreground job	fg %1
nohup	Run a command immune to hangups	nohup command &

Pipes & Redirection

Command	What it does	Example
\|	Pipe output to another command	command1 \| command2
>	Redirect output to a file	command > file.txt
>>	Append output to a file	command >> file.txt
<	Redirect input from a file	command < file.txt
2>&1	Redirect stderr to stdout	command 2>&1
/dev/null	Discard output	command > /dev/null

Text Processing

Command	What it does	Example
sed	Stream editor for filtering and transforming text	sed 's/old/new/' file.txt
awk	Pattern scanning and processing language	awk '{print $1}' file.txt
cut	Remove sections from each line of files	cut -d',' -f1 file.txt
sort	Sort lines of text files	sort file.txt
uniq	Report or omit repeated lines	uniq file.txt
tr	Translate or delete characters	tr 'a-z' 'A-Z' file.txt
xargs	Build and execute command lines from standard input	find /path/to/search -name "*.txt" \| xargs rm

Archives & Transfer

Command	What it does	Example
tar -czf	Create a compressed tar archive	tar -czf archive.tar.gz /path/to/directory
tar -xzf	Extract a compressed tar archive	tar -xzf archive.tar.gz
scp	Secure copy files between hosts	scp file.txt user@remote_host:/path/to/destination
rsync	Synchronize files and directories	rsync -av /path/to/source user@remote_host:/path/to/destination
curl	Transfer data with URLs	curl -O http://example.com/file.txt
wget	Non-interactive network downloader	wget http://example.com/file.txt