How CLI Invocation Works

Binary name is claude. Installed via npm (npm install -g claude), Homebrew, or direct download.
Default mode is interactive REPL. Passing a prompt as a positional argument runs one-shot and exits (unless --no-session-persistence or similar mode is active).
Subcommands dispatch separate workflows: claude config, claude mcp, claude plugin, claude auth, etc. run dedicated commands rather than starting the REPL.
Flags use --long-form with -s short-form. Boolean flags accept both --flag and --no-flag forms; some flags have both long and short options (e.g., -p / --print, -c / --continue).
Flag precedence: CLI flag > environment variable > settings.json. CLI arguments override both env vars and persisted settings.
Stdin is read when non-TTY input is detected or --print / -p is passed. This allows piping content for processing: cat logs.txt | claude -p "analyze".
Exit codes: 0 = success, non-zero = error. Use $? to check the exit status in scripts.