Wildcards & globbing *, ?, []

Wildcards and globbing in Linux are among the most commonly used shell features, yet many users rely on them without fully understanding how they work. A simple pattern such as * or ? can save time when managing files, but it can also produce unexpected results if used incorrectly.

This guide explains how wildcard patterns and globbing work in Bash, what happens behind the scenes when the shell expands a pattern, and how to use them safely in real-world scenarios. By the end of this article, you'll understand when to use each wildcard, how Bash interprets patterns, and how to avoid common mistakes when working across different Linux distributions.

Examples

Globbing is the shell expanding a pattern into a list of matching filenames before it ever hands those names to the command you typed. Nothing fancy is happening inside ls or rm or cp when you use *.log. Those commands never see the asterisk at all. Bash looks at the pattern, scans the current directory, builds the list of matches, and substitutes that list right there on the command line.

That distinction matters more than it sounds like it should. The term comes from an old Unix program literally called glob, short for "global", which did exactly this kind of pattern expansion before it got baked into the shell itself. Today every POSIX shell, bash, zsh, dash, all implement the same basic glob behavior, even though each one has its own extra tricks layered on top.

Think about the last time you typed ls *.conf to eyeball every config file in a directory. You weren't asking ls to understand wildcards. You were asking bash to do the matching, then handing ls a clean list of real filenames. Once that clicks, half the "weird" globbing behavior you'll run into later stops being weird.

There is no separate "glob command" to run. You just drop these characters straight into any command that takes a filename or path.

* matches zero or more of any character. ? matches exactly one character, no more, no less. [...] matches exactly one character that is a member of the set or range you give it, and putting ! or ^ right after the opening bracket flips that into "anything except these". None of this touches hidden files, anything starting with a dot, unless you tell the shell otherwise, and none of it goes into subdirectories on its own.

The most common reason anyone reaches for a wildcard. You want every log file in a directory without typing each name.

You've got numbered files and want to grab a fixed range without listing every name by hand.

Same numbered files, but now you only want a specific slice of them.

You want every numbered file except one specific number.

You don't care where the keyword sits in the filename, just that it's in there somewhere.

Brace expansion isn't technically a glob, but you'll use it next to globs constantly, so it earns a spot here.

You want every .conf file under a directory tree, not just the top level. By default a glob will not walk into subdirectories on its own, so this needs an extra shell option turned on first.

By default, an asterisk skips anything starting with a dot. Sometimes you genuinely need dotfiles included, like when auditing a home directory.

A real-world scenario from rotating logs. You want only this month's logs out of a folder going back years.

Another real-world case, the kind of one-liner that ends up inside a maintenance script run by cron at 2am.

This is close to the exact mistake from the intro, and it's worth seeing in full so the failure mode is obvious.

Getting comfortable with wildcards and globbing in Linux is what separates a careful sysadmin from someone who gets lucky most of the time. The moment you put a glob in front of a destructive command like rm, mv, or chmod -R, you've handed the shell a decision-making role in something irreversible. On a personal laptop a bad match costs you an afternoon of restoring from backup. On a production server it costs you an incident report and a very uncomfortable conversation, because a quoted versus unquoted pattern in a deployment script can be the difference between deleting one stale release folder and deleting every release folder on the box.

Mastering globbing changes how you write one-liners and scripts permanently. You stop reaching for find for things a simple pattern already handles, and you start reaching for find the moment you actually need recursion, time filters, or permission checks that a glob alone can't do. According to the GNU Bash Reference Manual, pattern matching behavior can also shift slightly depending on shell options like nocaseglob and extglob, which is exactly why the same script can behave differently across two servers that both claim to be running bash.