ncdu
CLINCurses disk usage analyzer with an interactive interface.
lsof
CLIList open files and the processes that opened them.
tar
CLICreate, list, and extract .tar / .tar.gz archives. Preinstalled on macOS and Linux.
zip / unzip
CLICreate and extract .zip archives. Preinstalled on macOS and most Linux images.
openssl
CLIGenerate random secrets, encode/decode base64, and hash files. Preinstalled on macOS and Linux.
shasum
CLICompute and verify SHA checksums. Ships with Perl on macOS and Linux.
sqlite3
CLICommand-line shell for SQLite databases. Preinstalled on macOS; apt install sqlite3 on Linux.
psql
CLIPostgreSQL interactive terminal, used non-interactively for one-shot queries and scripts.
timeout (coreutils)
CLIRun a command with a time limit. Part of GNU coreutils: built into Linux, 'gtimeout' on macOS after brew install coreutils.
poppler (pdftotext / pdftoppm)
CLIPDF text extraction, page info, and PDF → PNG rendering. The reliable way to read PDFs from a shell.
Chrome headless
CLIScreenshot or print any web page (local file or URL) to PNG/PDF with the browser you already have.