> Terminal cheatsheet

Learn essential commands for macOS & Linux

Navigation

Command	What it does	Notes
`cd`[dir]	Change working directory	`cd ~` goes home, `cd -` goes back to previous dir
`ls`[-la]	List directory contents	macOS `ls -G` for colour; Linux `ls --color`
`pwd`	Print working directory path
`pushd`[dir]	Push directory onto stack and switch to it	Pairs with `popd` to jump back
`popd`	Pop directory off stack and return to it	`dirs` shows the current stack

File management

Command	What it does	Notes
`cp`[-r] src dst	Copy files or directories	`-r` required for directories
`mv`src dst	Move or rename files	Works across directories; also renames in-place
`rm`[-rf] file	Remove files or directories	`-r` for dirs, `-f` to skip prompts — use carefully
`mkdir`[-p] dir	Create a directory	`-p` creates parent dirs as needed
`touch`file	Create an empty file or update its timestamp
`ln`[-s] src dst	Create a hard or symbolic link	`-s` for symlink; omit for hard link

Viewing files

Command	What it does	Notes
`cat`file	Print file contents to stdout	`cat -n` shows line numbers
`less`file	Page through a file interactively	`/term` to search, `q` to quit
`head`[-n N] file	Show first N lines of a file	Default is 10 lines
`tail`[-n N] file	Show last N lines of a file	`-f` follows live output (e.g. logs)
`wc`[-lwc] file	Count lines, words, or bytes	`-l` lines, `-w` words, `-c` bytes

Permissions

Command	What it does	Notes
`chmod`mode file	Change file permissions	`chmod 755 file` or `chmod +x file`
`chown`user[:group] file	Change file owner and/or group	`-R` applies recursively to directories
`sudo`command	Run a command as superuser	`sudo -i` opens a root shell
`su`[user]	Switch to another user account	`su -` loads the user's full environment

Processes

Command	What it does	Notes
`ps`[-aux]	List running processes	`ps aux` shows all processes with CPU/mem
`kill`[-9] PID	Send a signal to a process by PID	`-9` (SIGKILL) forces immediate termination
`killall`name	Kill all processes matching a name	`killall -9 node` force-kills all node processes
`top`	Interactive process monitor	macOS quit with `q`; Linux `k` to kill, `q` to quit
`htop`	Enhanced interactive process viewer	Install via Homebrew (macOS) or apt/dnf (Linux); mouse-friendly
`jobs`	List background jobs in current shell	Shows job numbers used by `bg` / `fg`
`bg`%N	Resume a stopped job in the background	`Ctrl+Z` to stop the current process first
`fg`%N	Bring a background job to the foreground	Omit `%N` for the most recent job

Networking

Command	What it does	Notes
`ping`host	Test reachability of a host	macOS runs indefinitely by default; use `-c N` to limit
`curl`[-X POST] url	Transfer data to/from a URL	`-o file` saves output, `-I` headers only, `-s` silent
`wget`url	Download a file from a URL	Not built-in on macOS — install via Homebrew; `-r` recursive
`ssh`user@host	Open a secure shell connection	`-i key.pem` to specify identity file, `-p` for custom port
`scp`src user@host:dst	Copy files securely over SSH	`-r` for directories; same syntax reversed to pull files
`netstat`[-tulnp]	Show network connections and listening ports	Linux prefer `ss -tulnp` on modern systems; netstat deprecated
`ss`[-tulnp]	Socket statistics — faster netstat replacement	Linux only; not available on macOS

Search & text

Command	What it does	Notes
`grep`[-r] pattern file	Search for a pattern in files	`-i` case-insensitive, `-n` line numbers, `-r` recursive
`find`path -name "*.ext"	Find files matching criteria	`-type f` files only, `-mtime -1` modified in last day
`sed`'s/old/new/g' file	Stream editor — transform text	macOS `sed -i ''` for in-place; Linux `sed -i` (no quotes needed)
`awk`'{print $1}' file	Pattern-action text processing	`-F:` sets field separator; `$NF` is the last field
`sort`[-n] file	Sort lines of text	`-n` numeric sort, `-r` reverse, `-u` unique
`uniq`[-c] file	Filter or count adjacent duplicate lines	Usually piped from `sort`; `-c` prefixes count

Pipes & redirection

Operator	What it does	Notes
`\|`	Pipe stdout of one command to stdin of next	`ls -la \| grep ".txt"`
`>`	Redirect stdout to a file, overwriting it	`echo "hello" > file.txt`
`>>`	Append stdout to a file	`echo "line" >> file.txt`
`<`	Redirect file contents to stdin	`wc -l < file.txt`
`2>&1`	Redirect stderr to stdout	`command > out.txt 2>&1` captures all output
`tee`file	Write stdin to file and also pass it through	`cmd \| tee out.log` — see it and save it; `-a` to append

Good to know

Command	What it does	Notes
`history`	Show command history	`!N` re-runs command N; `!!` re-runs the last command
`alias`name='cmd'	Create a shorthand for a command	Add to `~/.bashrc` or `~/.zshrc` for persistence
`env`	List all environment variables	`env VAR=val cmd` sets a var just for one command
`export`VAR=value	Set an environment variable for child processes	Without `export`, the variable stays in the current shell only
`which`command	Show the full path of an executable	Useful to confirm which version of a tool is being run
`man`command	Open the manual page for a command	`/term` to search within man; `q` to quit
`echo`text	Print text to stdout	`-n` suppresses trailing newline; `-e` enables escape sequences
`xargs`command	Build and run commands from stdin	`find . -name "*.log" \| xargs rm`; `-I{}` for placeholders

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