Globbing vs Regex

LPIC1-101LINUX

2/28/2026

1. The Core Difference

The most important distinction is where they are used:

Globbing (Wildcards): Used by the Shell (bash, zsh) to match file names or paths. When you type ls *.txt, the shell expands that list before the command even runs.
Regex (Regular Expressions): Used by Engines (grep, sed, python, awk) to look inside strings or files to find specific patterns of text.

Comparison Table

Feature Globbing (Shell) Regex (Text Processing)

* Matches any number of characters. Matches zero or more of the previous character.

? Matches exactly one character. Matches zero or one of the previous character. (optional character)

. Matches a literal dot. Matches any single character.

Usage rm *.log grep "E[0-9]\{3\}" data.txt

2. The "Star" Trap * and ?

This is the #1 cause of confusion.

In Globbing: a* means "anything starting with 'a'".
In Regex: a* means "the letter 'a', repeated any number of times (including zero)." To match "anything" in Regex, you have to use .* (Any character . repeated any number of times *).

The ? could be also particularly confusing:

In Globbing: ? is a placeholder for exactly one character (any character).
In Regex: ? is a quantifier meaning "zero or one" of whatever came immediately before it. It makes the preceding character optional.

3. Practical Examples

Globbing (The Shell expands this)

# Delete every file ending in .tmp

rm *.tmp

# List files named 'file1', 'file2', or 'fileA'

ls file[12A]

Regex (The Command interprets this)

# Find lines in a file that start with "Error"

grep "^Error" logfile.txt

# Find a 3-digit number

grep -E "[0-9]{3}" data.txt

How to keep them separate in your head

When you see a command, ask yourself: "Am I looking for a file on the disk, or am I looking for text inside a stream?"

File on disk? You’re Globbing.
Text in a stream/file? You’re using Regex.

Try the following,

4. BRE (Basic Regex) vs ERE (Extended Regex)

When you see a complex pattern with lots of backslashes before special characters, it is most certainly BRE. If the pattern looks "clean" but uses +, ?, or |, it is ERE.

Standard grep = BRE

grep -E = ERE

sed = BRE (by default)

sed -r = ERE

Some examples you can practice,

Looking for more grep flags? Try these.