expansion-practice-solution.md

Solution: Mastering Shell Expansions

Certainly! Below are the solutions for each task in your practice exercise on shell expansions in the Linux command line.

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Solution for Task 1: Simple Expansion

Objective: Use simple expansion to echo the current user and home directory.

Solution:

echo "Current user: $USER, Home directory: $HOME"

This command uses variable expansion to print the current username and home directory.

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Solution for Task 2: Pathname Expansion

Objective: Use pathname expansion to list all .txt files in the current directory.

Solution:

ls *.txt

Using the * wildcard, this command lists all .txt files in the current directory.

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Solution for Task 3: Tilde Expansion

Objective: Use tilde expansion to navigate to the home directory and then to a sub-directory Documents within it, all in a single command.

Solution:

cd ~/Documents

The tilde (~) expands to the home directory, so this command changes the current working directory to Documents within the home directory.

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Solution for Task 4: Brace Expansion

Objective: Create directories for each week in a course that lasts 12 weeks. The directories should be named Week1, Week2, ..., Week12.

Solution:

mkdir Week{1..12}

Brace expansion makes it easy to create multiple directories with a single command. This creates 12 directories, from Week1 to Week12.

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Solution for Task 5: Pathname Expansion (Advanced)

Objective: List all .txt and .pdf files in the current directory using pathname expansion.

Solution:

ls *.{txt,pdf}

This command uses brace expansion within pathname expansion to list all files that have either a .txt or .pdf extension.

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Solution for Task 6: Parameter Expansion

Objective: Create a variable named greeting with the value Hello. Use parameter expansion to echo the value of this variable.

Solution:

greeting="Hello"
echo $greeting

This sets a variable greeting with the value "Hello" and then uses parameter expansion to echo its value.