PATH variable management in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this PATH modification?

Consider the following commands run in a Linux shell:

export PATH=/usr/local/bin:$PATH

What will be the first directory in the PATH variable after running this command if the original PATH was /usr/bin:/bin?

Linux CLI

export PATH=/usr/local/bin:$PATH
echo $PATH

A /usr/local/bin:/usr/bin:/bin

B /usr/bin:/bin:/usr/local/bin

C /bin:/usr/bin:/usr/local/bin

D /usr/bin:/usr/local/bin:/bin

💡 Hint

Remember that placing a directory before $PATH adds it to the front.

The command prepends /usr/local/bin to the existing PATH, so it becomes the first directory.

💻 Command Output

intermediate

What happens if you append an empty directory to PATH?

Given the command:

export PATH=$PATH::/usr/bin

What is the effect of the double colon (::) in the PATH variable?

Linux CLI

export PATH=$PATH::/usr/bin
echo $PATH

A It inserts the current directory (.) in the PATH at the position of the empty entry

B It causes a syntax error and PATH is not updated

C It removes the last directory from PATH

D It adds an empty directory that is ignored by the shell

💡 Hint

Empty entries in PATH are interpreted as the current directory.

In PATH, an empty entry between colons means the current directory (.) is included at that position.

📝 Syntax

advanced

Which command correctly removes /usr/local/bin from PATH?

You want to remove /usr/local/bin from the PATH variable in a bash shell. Which of the following commands will do this correctly?

A export PATH=$(echo $PATH | sed -e 's|:/usr/local/bin:||')

B export PATH=$(echo $PATH | sed -e 's|:/usr/local/bin||')

C export PATH=$(echo $PATH | sed -e 's|/usr/local/bin||')

D export PATH=$(echo $PATH | sed -e 's|/usr/local/bin:||')

💡 Hint

Consider the position of /usr/local/bin in PATH and the colon separators.

Option D removes /usr/local/bin only if it is at the start followed by a colon, avoiding partial matches elsewhere.

💻 Command Output

advanced

What is the output of this PATH check script?

Given this bash script snippet:

if [[ ":$PATH:" == *":/opt/bin:"* ]]; then
echo "Found"
else
echo "Not Found"
fi

What will be printed if PATH is /usr/bin:/opt/bin:/bin?

Linux CLI

PATH=/usr/bin:/opt/bin:/bin
if [[ ":$PATH:" == *":/opt/bin:"* ]]; then
echo "Found"
else
echo "Not Found"
fi

A No output

B Syntax error

C Found

D Not Found

💡 Hint

The script adds colons around PATH to avoid partial matches.

The pattern matches :/opt/bin: inside :$PATH:, so it prints Found.

🚀 Application

expert

How to permanently add a directory to PATH for all users?

You want to add /custom/tools to the PATH environment variable permanently for all users on a Linux system. Which file is the best place to add this export command to achieve this?

A /root/.bash_profile

B /etc/profile

C /etc/bash.bashrc

D ~/.bashrc

💡 Hint

Think about system-wide environment variables for all users.

/etc/profile is executed for login shells for all users, making it the best place for system-wide PATH changes.