File globbing (wildcards *, ?, []) in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What files match this pattern?

Given a directory containing files:
report1.txt, report2.txt, report_final.txt, summary.txt, data.csv
What files will match the pattern report?.txt?

A report1.txt, report2.txt, report_final.txt

B report1.txt, report2.txt

C report_final.txt

D summary.txt, data.csv

💡 Hint

The question mark matches exactly one character.

The pattern report?.txt matches files starting with 'report', followed by exactly one character, then '.txt'. So it matches 'report1.txt' and 'report2.txt' but not 'report_final.txt' because it has more than one character after 'report'.

💻 Command Output

intermediate

Which files match the pattern with brackets?

In a folder with files: data1.csv, data2.csv, data3.csv, dataA.csv, dataB.csv
Which files match the pattern data[12].csv?

A data1.csv, data2.csv, data3.csv

B data3.csv

C dataA.csv, dataB.csv

D data1.csv, data2.csv

💡 Hint

Square brackets match exactly one character from the set inside.

The pattern data[12].csv matches files where the character after 'data' is either '1' or '2'. So it matches 'data1.csv' and 'data2.csv' only.

📝 Syntax

advanced

Identify the correct glob pattern for matching files ending with .log or .txt

Which of the following patterns correctly matches files that end with either .log or .txt?

A *.{log,txt}

B *.[log|txt]

C *.[log,txt]

D *.(log|txt)

💡 Hint

Brace expansion is used to match multiple extensions.

The pattern *.{log,txt} uses brace expansion to match files ending with either '.log' or '.txt'. The other options use invalid syntax for globbing.

💻 Command Output

advanced

What is the output of this glob pattern?

Given files: file1.txt, file2.txt, file10.txt, file20.txt, fileA.txt
What files match the pattern file?.txt?

A file1.txt, file2.txt, fileA.txt

B file1.txt, file2.txt

C file10.txt, file20.txt

D fileA.txt

💡 Hint

The question mark matches exactly one character.

The pattern file?.txt matches files with exactly one character after 'file' before '.txt'. So it matches 'file1.txt', 'file2.txt', and 'fileA.txt'. It does not match 'file10.txt' or 'file20.txt' because they have two characters after 'file'.

🧠 Conceptual

expert

How many files match this complex pattern?

In a directory with files: a1.txt, a2.txt, a10.txt, b1.txt, b2.txt, c1.txt
How many files match the pattern [ab]?*.txt?

A 3

B 4

C 5

D 6

💡 Hint

The pattern matches files starting with 'a' or 'b', followed by at least one character, then any characters, ending with '.txt'.

The pattern [ab]?*.txt matches files starting with 'a' or 'b', then at least one character (due to '?'), then zero or more characters (due to '*'), ending with '.txt'. The matched files are: a1.txt, a2.txt, a10.txt, b1.txt, b2.txt. The file c1.txt does not match because it starts with 'c'. So total matched files are 5.