opscape

Shell reference · 149 commands · 1894 examples

Every command,
run and explained.

Shell references usually show you what a command should print. Here, every example ran in Debian 13.7 against the same small project directory, and the output under it is exactly what came back, error messages and exit codes included.

grep ERROR logs/app.log
2026-03-14 08:16:40 ERROR health check failed: database timeout after 5000ms
2026-03-14 08:30:00 ERROR disk usage on /var at 91%

Real output, from the grep page.

Commands by task

All 149 commands

Files and directories

Create, copy, move, link and inspect files and directories.

Viewing files

Look inside files: the start, the end, line counts and raw bytes.

Text processing

Filter, cut, sort, transform and compare text, the shell's real superpower.

Archives and compression

Pack, compress and unpack tarballs, zips and friends.

Processes and jobs

See what is running, stop it, background it, time it.

System and users

Who you are, what the machine is doing, dates, services and logs.

Disks and filesystems

Space used, space free, and what is mounted where.

Networking and remote

HTTP requests, remote shells, file sync and sockets.

Shell builtins

Commands built into bash itself: variables, options, tests and control.

Bash scripting guide

32 parts

From the #! line at the top of a script to traps, strict mode and portable sh, with every example run and its real output shown. Quoting gets the attention it deserves: it causes more shell bugs than anything else.

  1. The shebang line
  2. Running scripts
  3. Variables
  4. Environment variables
  5. Quoting
  6. Word splitting
  7. Parameter expansion
  8. Command substitution
  9. Arithmetic
  10. Arrays

The whole guide

Explain and print

Explain a command line Paste a one-liner from a script or a forum post. It is split into the pieces bash sees (pipes, redirections, quotes, variables, globs, subshells) and each option is looked up in this site's own notes. Unknown options are flagged, never guessed. Runs in your browser; nothing is sent anywhere. Printable cheat sheets 14 one-page sheets, by topic: text processing, files, networking, parameter expansion, test operators, redirection and more. Every line checked by running it. How the examples are run A pinned Debian image, a fixed sample project, 1851 examples run on every rebuild. If an example's exit status changes, the site does not publish.