Terminal

Bash essentials for navigating, searching, piping and managing files.

Command	Description
`pwd`	Print current directory
`ls -la`	List all files with details
`cd <dir>`	Change directory
`cd -`	Go to previous directory
`cd ~`	Go home
`tree -L 2`	Folder tree, 2 levels deep

Files and folders

Command	Description
`touch file.txt`	Create empty file
`mkdir -p a/b/c`	Create nested folders
`cp -r src dest`	Copy folder
`mv old new`	Move or rename
`rm file`	Delete file
`rm -r folder`	Delete folder
`ln -s target link`	Symbolic link

Viewing files

Command	Description
`cat file`	Print file
`less file`	Scroll through file (`q` to quit)
`head -n 20 file`	First 20 lines
`tail -n 20 file`	Last 20 lines
`tail -f app.log`	Follow a file as it grows
`wc -l file`	Count lines

Searching

Command	Description
`grep "text" file`	Lines containing text
`grep -rn "text" .`	Recursive with line numbers
`grep -i` / `-v`	Case insensitive / invert match
`find . -name "*.js"`	Find files by name
`find . -type d -name node_modules`	Find folders
`find . -mtime -1`	Modified in last 24h
`which node`	Location of a command

Pipes and redirection

Syntax	Description
`a \| b`	Pipe output of a into b
`> file`	Write output to file (overwrite)
`>> file`	Append output to file
`2> file`	Redirect errors
`&> file`	Redirect output and errors
`a && b`	Run b if a succeeds
`a \|\| b`	Run b if a fails
`a ; b`	Run b after a regardless

cat access.log | grep 404 | sort | uniq -c | sort -rn | head
find . -name "*.tmp" | xargs rm

Processes

Command	Description
`ps aux`	All processes
`top` / `htop`	Live process view
`kill <pid>`	Stop a process
`kill -9 <pid>`	Force kill
`command &`	Run in background
`jobs` / `fg`	List / resume background jobs
`Ctrl+C` / `Ctrl+Z`	Interrupt / suspend

Permissions

Command	Description
`chmod +x script.sh`	Make executable
`chmod 644 file`	rw-r–r–
`chmod 755 dir`	rwxr-xr-x
`chown user:group file`	Change owner
`sudo <command>`	Run as root

Shortcuts and history

Shortcut	Description
`Ctrl+R`	Search command history
`!!`	Repeat last command (`sudo !!`)
`Ctrl+A` / `Ctrl+E`	Start / end of line
`Ctrl+U` / `Ctrl+K`	Delete before / after cursor
`Ctrl+L`	Clear screen
`history`	Show command history

Network

Command	Description
`curl -I <url>`	Response headers only
`curl -X POST -d '{}' -H "Content-Type: application/json" <url>`	POST JSON
`wget <url>`	Download file
`ssh user@host`	Connect over SSH
`scp file user@host:/path`	Copy file over SSH