File globbing (wildcards *, ?, []) in Linux CLI - Step-by-Step Execution

Concept Flow - File globbing (wildcards *, ?, [])

Start: User inputs pattern

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Shell reads pattern

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Match *: any chars

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Match ?: single char

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Match [

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List matching files

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Output matched filenames

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End

The shell reads the pattern, matches files using wildcards (*, ?, []), then lists all matching filenames.

Execution Sample

Linux CLI

ls *.txt
ls file?.sh
ls data[0-9].csv

These commands list files matching patterns with *, ?, and [] wildcards.

Execution Table

Step	Command	Pattern	Files in folder	Matched Files	Output
1	ls *.txt	*.txt	file1.txt, file2.txt, fileA.sh, data1.csv	file1.txt, file2.txt	file1.txt file2.txt
2	ls file?.sh	file?.sh	file1.txt, file2.txt, fileA.sh, fileB.sh, file10.sh	fileA.sh, fileB.sh	fileA.sh fileB.sh
3	ls data[0-9].csv	data[0-9].csv	data1.csv, data2.csv, dataA.csv	data1.csv, data2.csv	data1.csv data2.csv
4	ls data[!0-9].csv	data[!0-9].csv	data1.csv, data2.csv, dataA.csv	dataA.csv	dataA.csv
5	ls *.md	*.md	file1.txt, README.md	README.md	README.md
6	ls file?.sh	file?.sh	file1.txt, file2.txt, fileA.sh, fileB.sh, file10.sh	fileA.sh, fileB.sh	fileA.sh fileB.sh
7	ls file??.sh	file??.sh	file1.txt, file2.txt, fileA.sh, fileB.sh, file10.sh	file10.sh	file10.sh
8	ls *.xyz	*.xyz	file1.txt, file2.txt

💡 No more commands to process; last pattern matches no files, so output is empty.

Variable Tracker

Variable	Start	After 1	After 2	After 3	After 4	After 5	After 6	After 7	After 8
Pattern		*.txt	file?.sh	data[0-9].csv	data[!0-9].csv	*.md	file?.sh	file??.sh	*.xyz
Matched Files		file1.txt,file2.txt	fileA.sh,fileB.sh	data1.csv,data2.csv	dataA.csv	README.md	fileA.sh,fileB.sh	file10.sh

Key Moments - 3 Insights

Why does 'file?.sh' match 'fileA.sh' but not 'file10.sh'?

'file?.sh' matches exactly one character in place of '?'. 'fileA.sh' has one character 'A' after 'file', but 'file10.sh' has two characters '10', so it does not match. See execution_table rows 2 and 6.

What does the pattern 'data[0-9].csv' mean?

It matches files starting with 'data', followed by exactly one digit from 0 to 9, then '.csv'. So 'data1.csv' matches but 'dataA.csv' does not. See execution_table row 3.

What happens if no files match the pattern?

The command outputs nothing (empty). For example, '*.xyz' matches no files in the folder, so output is empty. See execution_table row 8.

Visual Quiz - 3 Questions

Look at the execution table, what files does 'ls file?.sh' match at step 2?

A file10.sh

B file1.txt, file2.txt

C fileA.sh, fileB.sh

D fileA.sh, file10.sh

💡 Hint

Check the 'Matched Files' column at step 2 in the execution_table.

At which step does the pattern match no files?

A Step 5

B Step 8

C Step 3

D Step 1

💡 Hint

Look for empty 'Matched Files' in the execution_table.

If we change 'file?.sh' to 'file??.sh', which file matches?

A file10.sh

B fileB.sh

C fileA.sh

D file1.txt

💡 Hint

Check step 7 in execution_table for 'file??.sh' pattern.

Concept Snapshot

File globbing uses wildcards to match filenames:
* matches any number of characters
? matches exactly one character
[] matches any one character inside brackets
Patterns help list files easily in commands like ls.

Full Transcript

File globbing is how the shell matches filenames using wildcards. The star (*) matches any number of characters, question mark (?) matches exactly one character, and square brackets ([]) match any one character from a set. For example, '*.txt' matches all files ending with .txt. The shell reads the pattern, finds matching files, and lists them. If no files match, the output is empty. Patterns like 'file?.sh' match files with exactly one character after 'file' and before '.sh'. This helps quickly find files without typing full names.