Looping over files and directories in Bash Scripting - Cheat Sheet & Quick Revision

Recall & Review

beginner

What command is commonly used in bash to loop over all files in a directory?

The for loop is commonly used with a wildcard pattern like for file in *; do ... done to loop over all files in the current directory.

beginner

How do you loop over only directories in bash?

Use a pattern that matches directories, for example: for dir in */; do ... done. The trailing slash / ensures only directories are matched.

beginner

What does the following script do?<br>

for file in *.txt; do echo "$file"; done

It loops over all files ending with .txt in the current directory and prints each filename on its own line.

intermediate

Why should you quote variables like "$file" inside loops?

Quoting variables prevents word splitting and preserves spaces or special characters in filenames, avoiding errors during processing.

intermediate

How can you loop over files recursively in bash?

You can use the find command with a loop, for example:<br>find . -type f -name "*.txt" -exec bash -c 'echo "$0"' {} \; or use a while read loop with find and read.

Which pattern matches only directories in a bash for loop?

A */

B *

C *.txt

D .*

The pattern */ matches only directories because the trailing slash indicates directories.

What is the purpose of quoting variables like "$file" inside loops?

A To prevent word splitting and handle spaces in filenames

B To make the script run faster

C To convert filenames to uppercase

D To ignore hidden files

Quoting variables prevents word splitting and preserves spaces or special characters in filenames.

How do you loop over all .txt files in the current directory in bash?

A while read file; do ... done < *.txt

B for file in *; do if file ends with .txt; done

C loop *.txt

D for file in *.txt; do ... done

The for file in *.txt; do ... done syntax loops over all files ending with .txt.

Which command helps to loop over files recursively in bash?

A ls -R

B find

C grep

D cat

The find command is used to search files recursively and can be combined with loops.

What does the wildcard * match in bash?

A Only files starting with a dot

B Only files with extensions

C All files and directories except hidden ones

D Only directories

The wildcard * matches all files and directories except hidden ones (those starting with a dot).

Explain how to loop over all files in a directory using bash scripting.

Think about using a for loop with * and why quoting matters.

Describe how to loop over directories only and why the pattern differs from looping over files.

Directories end with a slash in patterns.