export command in Linux CLI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the environment variable MY_VAR to 'hello' using export.

Linux CLI

export MY_VAR=[1]

Drag options to blanks, or click blank then click option'

Ahello

B'hello'

C"hello"

DHELLO

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes can cause errors if the value has spaces or special characters.

Using uppercase without quotes sets a different value.

The export command sets environment variables. To assign a string with spaces or special characters, use quotes. Here, 'hello' is correctly quoted with single quotes.

2fill in blank

medium

Complete the code to export the PATH variable by adding '/usr/local/bin' at the end.

Linux CLI

export PATH=$PATH[1]/usr/local/bin

Drag options to blanks, or click blank then click option'

A:

B;

C,

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using semicolon ';' which is for Windows paths.

Using plus '+' or comma ',' which are invalid separators.

In Linux, PATH entries are separated by colons ':'. To add a new directory, append it with a colon separator.

3fill in blank

hard

Fix the error in the code to export a variable named DATA_DIR with the value '/data/files'.

Linux CLI

export [1]='/data/files'

Drag options to blanks, or click blank then click option'

Adata_dir

Bdata-dir

CDataDir

DDATA_DIR

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or mixed case variable names.

Using dashes '-' which are invalid in variable names.

Environment variable names should be uppercase and cannot contain dashes. DATA_DIR is the correct format.

4fill in blank

hard

Fill both blanks to export a variable named CONFIG_PATH with the value '/etc/config'.

Linux CLI

export [1]=[2]

Drag options to blanks, or click blank then click option'

ACONFIG_PATH

B'/etc/config'

C"/etc/config"

Dconfig_path

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase variable names.

Not quoting the value.

Variable names should be uppercase with underscores. The value should be quoted to handle special characters.

5fill in blank

hard

Fill all three blanks to export a variable named LIB_PATH by adding '/usr/lib' to the existing LIB_PATH.

Linux CLI

export [1]=$[2]:[3]

Drag options to blanks, or click blank then click option'

ALIB_PATH

C/usr/lib

D/usr/local/lib

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names in export and reference.

Using wrong path or separator.

To add a directory to an existing variable, use the variable name on both sides and separate with a colon. Here, LIB_PATH is updated by appending '/usr/lib'.

Practice

1. What does the export command do in a Linux shell?

easy

A. Makes a shell variable available to child processes

B. Deletes a shell variable permanently

C. Lists all files in the current directory

D. Changes the current directory

Solution

1. Step 1: Understand shell variables and environment

   Shell variables exist only in the current shell session unless exported.

2. Step 2: Role of export

   The export command marks a variable to be passed to child processes as environment variables.

3. Final Answer:

   Makes a shell variable available to child processes -> Option A

4. Quick Check:

   export = share variable with child processes [OK]

Hint: Export shares variables with child processes [OK]

Common Mistakes:

• Thinking export deletes variables
• Confusing export with file commands
• Assuming export changes directories

2. Which of the following is the correct syntax to export a variable named PATH with value /usr/local/bin?

easy

A. export =PATH /usr/local/bin

B. export PATH=/usr/local/bin

C. export PATH : /usr/local/bin

D. export PATH == /usr/local/bin

Solution

1. Step 1: Recall export syntax

   The correct syntax is export VARIABLE=VALUE without spaces around the equal sign.

2. Step 2: Check each option

   export PATH=/usr/local/bin matches the correct syntax. Others have invalid characters or spaces.

3. Final Answer:

   export PATH=/usr/local/bin -> Option B

4. Quick Check:

   export VAR=VALUE no spaces [OK]

Hint: No spaces around = in export syntax [OK]

Common Mistakes:

• Adding spaces around equal sign
• Using wrong symbols like : or ==
• Placing export after assignment

3. What will be the output of the following commands?

MYVAR="hello"
echo $MYVAR
export MYVAR
bash -c 'echo $MYVAR'

medium

A. \n\n

B. hello\n

C. \nhello

D. hello\nhello

Solution

1. Step 1: Understand variable assignment and export

   First, MYVAR is set to "hello" and printed, so first echo outputs "hello". Then MYVAR is exported.

2. Step 2: Child shell access

   The bash -c 'echo $MYVAR' runs a new shell which inherits exported variables, so it prints "hello" again.

3. Final Answer:

   hello hello -> Option D

4. Quick Check:

   Exported variable visible in child shell [OK]

Hint: Exported vars visible in child shells [OK]

Common Mistakes:

• Assuming unexported vars appear in child shells
• Confusing echo outputs with command prompts
• Ignoring export effect on subshells

4. Identify the error in this script snippet:

export MYVAR
MYVAR="world"
echo $MYVAR

medium

A. echo command is missing quotes

B. export command syntax is wrong

C. MYVAR is exported before assignment, so child shells get empty value

D. No error, script works fine

Solution

1. Step 1: Analyze export before assignment

   Exporting MYVAR before assigning means MYVAR is empty when exported.

2. Step 2: Effect on variable value

   Assigning MYVAR after export does not update the exported environment variable for child processes.

3. Final Answer:

   MYVAR is exported before assignment, so child shells get empty value -> Option C

4. Quick Check:

   Export before assignment exports empty value [OK]

Hint: Assign before export to share correct value [OK]

Common Mistakes:

• Exporting before assigning value
• Thinking export syntax is wrong
• Assuming echo needs quotes always

5. You want to set a variable CONFIG_PATH to /etc/config and ensure it is available to all scripts run from your current shell session and its children. Which sequence of commands achieves this correctly?

hard

A. CONFIG_PATH=/etc/config\nexport CONFIG_PATH

B. export CONFIG_PATH=/etc/config

C. export CONFIG_PATH\nCONFIG_PATH=/etc/config

D. CONFIG_PATH=/etc/config

Solution

1. Step 1: Assign variable before export

   Assigning CONFIG_PATH=/etc/config sets the value in the current shell.

2. Step 2: Export variable after assignment

   Running export CONFIG_PATH marks it for child processes with the assigned value.

3. Step 3: Check other options

   export CONFIG_PATH=/etc/config works but is less clear; export CONFIG_PATH\nCONFIG_PATH=/etc/config exports before assignment (wrong); CONFIG_PATH=/etc/config does not export.

4. Final Answer:

   CONFIG_PATH=/etc/config export CONFIG_PATH -> Option A

5. Quick Check:

   Assign then export to share variable [OK]

Hint: Assign first, then export to share variable [OK]

Common Mistakes:

• Exporting before assigning value
• Not exporting variable at all
• Assuming single export with assignment is always best