Environment variables vs local variables in Bash Scripting - Practice Questions

Challenge - 5 Problems

💻 Command Output

intermediate

Output of local vs environment variable in subshell

What is the output of this script?

MYVAR="hello"
(export MYVAR; (echo $MYVAR))
echo $MYVAR

Bash Scripting

MYVAR="hello"
(export MYVAR; (echo $MYVAR))
echo $MYVAR

A hello\n

B \nhello

C hello\nhello

D \n

💡 Hint

Remember that exporting a variable makes it available to subshells.

The variable MYVAR is set locally and then exported, so the subshell can access it and print 'hello'. The final echo prints the local MYVAR which is still 'hello'.

💻 Command Output

intermediate

Effect of local variable inside function on environment

What is the output of this script?

MYVAR="start"
myfunc() {
  local MYVAR="inside"
  echo $MYVAR
}
myfunc
echo $MYVAR

Bash Scripting

MYVAR="start"
myfunc() {
  local MYVAR="inside"
  echo $MYVAR
}
myfunc
echo $MYVAR

A start\ninside

B inside\ninside

C start\nstart

D inside\nstart

💡 Hint

Local variables inside functions do not affect variables outside.

The function defines a local MYVAR which shadows the global one. Inside the function, it prints 'inside'. Outside, the original MYVAR remains 'start'.

🔧 Debug

advanced

Why environment variable is not updated in parent shell?

Consider this script:

export MYVAR="old"
(change_var() {
  MYVAR="new"
  export MYVAR
})
(change_var)
echo $MYVAR

Why does the echo print 'old' instead of 'new'?

Bash Scripting

export MYVAR="old"
(change_var() {
  MYVAR="new"
  export MYVAR
})
(change_var)
echo $MYVAR

A Because the function runs in a subshell, changes do not affect the parent shell

B Because export does not update existing environment variables

C Because MYVAR is local by default inside functions

D Because the variable was not declared with local keyword

💡 Hint

Think about where the function runs and how environment variables propagate.

The function runs inside parentheses, which creates a subshell. Changes to variables in a subshell do not affect the parent shell environment.

🧠 Conceptual

advanced

Difference between local and environment variables

Which statement correctly describes the difference between local and environment variables in bash?

A Local variables exist only within the current shell or function, environment variables are inherited by child processes

B Environment variables exist only within the current shell, local variables are inherited by child processes

C Local variables are automatically exported to child processes, environment variables are not

D Environment variables are temporary, local variables are permanent

💡 Hint

Think about variable visibility and inheritance.

Local variables are limited to the current shell or function scope. Environment variables are exported and passed to child processes.

🚀 Application

expert

Preserving environment variable changes after script execution

You have a script that sets and exports an environment variable MYVAR. After running the script normally, the variable is not set in your current shell. How can you modify your usage to have MYVAR set in your current shell after running the script?

A Run the script normally: ./script.sh

B Run the script with the source command: source ./script.sh

C Run the script in a new terminal window

D Add local MYVAR in the script before exporting

💡 Hint

Think about how environment variables propagate between shells.

Running the script with source executes it in the current shell, so environment variable changes persist after the script finishes.