String suffix removal (${var%pattern}) in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this suffix removal?

Given the variable assignment filename="report_final_v2.txt", what is the output of echo ${filename%.txt}?

Bash Scripting

filename="report_final_v2.txt"
echo ${filename%.txt}

A report_final_v2

B report_final_v2.txt

C report_final_v2.tx

D report_final_v2.t

💡 Hint

The % operator removes the shortest matching suffix pattern from the variable's value.

The pattern %.txt removes the shortest suffix matching '.txt' from the variable, so the output is 'report_final_v2'.

💻 Command Output

intermediate

Removing suffix with wildcard pattern

What is the output of this command?
path="/home/user/docs/file_backup.tar.gz"
echo ${path%.tar.*}

Bash Scripting

path="/home/user/docs/file_backup.tar.gz"
echo ${path%.tar.*}

A /home/user/docs/file_backup

B /home/user/docs/file_backup.tar

C /home/user/docs/file_backup.tar.gz

D /home/user/docs/file_backup.tar.g

💡 Hint

The pattern %.tar.* removes the shortest suffix starting with '.tar.'

The pattern %.tar.* removes the shortest suffix matching '.tar.' followed by anything, so it removes '.tar.gz' from the end.

📝 Syntax

advanced

Identify the correct suffix removal syntax

Which option correctly removes the shortest suffix matching '.log' from the variable file?

Bash Scripting

file="system_error.log"

A echo ${file%\.log}

B echo ${file%.log}

C echo ${file%log.}

D echo ${file%*.log}

💡 Hint

The pattern must match the suffix exactly as it appears.

Option B correctly uses %.log to remove the suffix '.log'. Option B uses wrong order, A escapes unnecessarily, D uses wildcard incorrectly.

🔧 Debug

advanced

Why does this suffix removal fail?

Given name="archive.tar.gz.bak", why does echo ${name%.tar.gz} output archive.tar.gz.bak instead of archive?

Bash Scripting

name="archive.tar.gz.bak"
echo ${name%.tar.gz}

A Because %.tar.gz removes the shortest suffix matching '.tar.gz', but the shell treats '.' as a wildcard and fails.

B Because %.tar.gz removes only the shortest suffix, but '.tar.gz' is the entire suffix so it matches and removes it.

C Because %.tar.gz removes the shortest suffix matching '.tar.gz', but the pattern must be quoted to work.

D Because %.tar.gz removes the shortest suffix matching '.tar.gz', but the pattern is treated literally and does not match the suffix.

💡 Hint

The pattern must match some suffix of the variable exactly.

The pattern %.tar.gz requires a suffix that exactly matches '.tar.gz'. Here, the value ends with '.tar.gz.bak', which does not have a suffix matching '.tar.gz', so nothing is removed. Dots are literal in these glob patterns.

🚀 Application

expert

Extract base filename without extension using suffix removal

You have a variable file="backup_2024-06-01.tar.gz". Which command correctly extracts the base filename backup_2024-06-01 by removing the longest suffix starting with the first dot?

Bash Scripting

file="backup_2024-06-01.tar.gz"

A echo ${file#*.}

B echo ${file%.*}

C echo ${file%%.*}

D echo ${file##*.}

💡 Hint

Use %% to remove the longest matching suffix pattern.

Option C uses %%.* to remove the longest suffix starting with a dot, leaving the base filename. Option C removes only the shortest suffix after the last dot, leaving 'backup_2024-06-01.tar'. Options C and D remove prefixes, not suffixes.