Run it, then check it
Open the terminal from last chapter. Type the installer command and press enter:
curl -fsSL https://claude.ai/install.sh | bash
The terminal prints a few lines as it downloads and sets things up. This takes under a minute. When it finishes, you get a fresh prompt.
Confirm it worked
Don't trust "it didn't error." Check directly. Type:
claude --version
If the install worked, this prints a version number, something like:
2.x.x (Claude Code)
A version number means the CLI is installed and your terminal can find
it. That's the whole confirmation. --version is an option (you met
options in the terminal chapter, a dash and a word that adjusts a
command). It tells claude to just report its version and quit, which
makes it a safe "are you there" check.
If it didn't work
The most common snag: you run claude --version and the terminal says
something like command not found: claude. That almost always means
the CLI installed fine but the terminal hasn't noticed it yet.
The fix is usually the simplest possible one: close the terminal
window completely and open a fresh one. A terminal checks for available
commands when it starts, so a brand-new window sees the freshly
installed claude. Run claude --version again in the new window.
If a fresh window still says command not found, that's a real
install issue, and Anthropic keeps a troubleshooting page for exactly
this. But the fresh window is often the fix. Try that first before
assuming anything is broken.