2. Supplementary - Quick reference guide

Common commands

Command	What it does
pwd	Print working directory
ls	List files and directories
cd	Change directory
mkdir	Make a new directory
cp	Copy a file or directory
mv	Move or rename a file or directory
rm	Remove a file
cat	Print file contents
head / tail	Print first / last lines of a file
wc	Count lines, words, or characters
grep	Search for a pattern in a file
cut	Extract columns from a file
sort	Sort lines
uniq	Filter duplicate neighbouring lines
>	Redirect output to a file (overwrites)
>>	Redirect output to a file (appends)
|	Pipe output from one command to another

Getting Unstuck

Tips for when things go wrong

• Ctrl + C cancels a running command and returns you to the prompt
• Ctrl + D signals "end of input" — useful for exiting an interactive cat session or closing a shell
• Ctrl + Z suspends a running process (type fg to resume it)
• q quits most pager views (e.g. man pages, less)
• If your prompt disappears or looks wrong, try pressing Enter a couple of times, or Ctrl + C
• An unclosed quote (' or ") will cause the prompt to hang — press Ctrl + C to escape
• man <command> or <command> --help are your friends when you forget a flag