Wildcards and Tab Completion

What this is. A wildcard lets one word stand for many filenames. The shell expands it before the command runs, so the command never sees the star at all.

* matches any run of characters, including none.

? matches exactly one character.

So ls *.js lists every file ending in .js, and ls app.?s matches app.js and app.ts but not app.jsx.

✦ The shell expands, not the command

This is the detail that explains a whole class of confusion. When you type ls *.js, the shell replaces *.js with the matching filenames and then runs ls with those as arguments. The command has no idea a wildcard was involved. It is also why an unquoted wildcard passed to find gets expanded too early, which you will meet in a moment.

Tab completion is not a shortcut, it is a correctness tool. Type the first few characters of a path and press Tab, and the shell finishes it. If several things match, pressing Tab twice lists them.

The real value is that a completed path is a path that exists. Most no such file errors are typing errors, and Tab eliminates them. Experienced users type remarkably few full filenames.