codex-lv2-may-2025

1 | 2 | 3 | 4 | 5 | 6 | Current Level: 7

Lesson: Work with Multiple Files Using Wildcards and Patterns

Objective

Learn how to copy, move, and list multiple files efficiently using wildcards and filename patterns in the Unix shell.

Step 1: Copy Multiple Files at Once

Use cp with multiple filenames and a target directory:

mkdir backup
cp creatures/minotaur.dat creatures/unicorn.dat backup/

Result: Both files are copied into the backup/ directory.

You can also list filenames directly:

cd creatures
cp minotaur.dat unicorn.dat basilisk.dat ../backup/

Step 2: Use Wildcards to Match File Patterns

Asterisk * matches zero or more characters:

ls *.pdb         # Matches all files ending in .pdb
ls p*.pdb        # Matches files starting with "p" and ending in .pdb

Question mark ? matches exactly one character:

ls ?ethane.pdb   # Matches methane.pdb
ls *ethane.pdb   # Matches both methane.pdb and ethane.pdb

Combine wildcards:

ls ???ane.pdb    # Matches cubane.pdb, ethane.pdb, octane.pdb

Step 3: Match a Specific Pattern

Given a directory of .pdb files, which of the following commands list ethane.pdb and methane.pdb?

ls *t*ane.pdb
ls *t?ne.*
ls *t??ne.pdb
ls ethane.*

Try each one to see which patterns match.

Step 4: Help Organize and Copy Files Using Wildcards

Sam wants to organize a set of dated .txt files. She uses wildcard patterns to copy selected files into subdirectories:

cp *dataset* backup/datasets
cp *calibration.txt backup/calibration
cp 2015-11-23-* send_to_bob/all_november_files/
cp *10-23-dataset* send_to_bob/all_datasets_created_on_a_23rd/
cp *11-23-dataset* send_to_bob/all_datasets_created_on_a_23rd/

Make sure destination folders (backup/, send_to_bob/) exist before running these commands.

Step 5: Move Files into Organized Folders

Jamie has disorganized files:

ls -F
# analyzed/  fructose.dat  raw/  sucrose.dat

To tidy up:

mv fructose.dat sucrose.dat analyzed/

Now:

ls -F
# analyzed/  raw/

ls analyzed
# fructose.dat  sucrose.dat

Step 6: Reproduce a Folder Structure for a New Experiment

Goal: Copy folder structure (not files) from 2016-05-18 to 2016-05-20.

Best command:

mkdir -p 2016-05-20/data/raw
mkdir -p 2016-05-20/data/processed

Other options (multi-line versions) also work, but are more verbose:

mkdir 2016-05-20
mkdir 2016-05-20/data
mkdir 2016-05-20/data/raw
mkdir 2016-05-20/data/processed

Reflection Questions

How do wildcards help automate file operations?
What are the benefits and risks of using wildcards in cp, mv, and rm?