BashOperator for shell commands in Apache Airflow - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the BashOperator from Airflow.

Apache Airflow

from airflow.operators.[1] import BashOperator

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

Apython

Bbash_operator

Cemail

Ddummy

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'python' instead of 'bash_operator' as the module name.

Confusing BashOperator with other operators like EmailOperator.

The BashOperator is imported from airflow.operators.bash_operator.

2fill in blank

medium

Complete the code to create a BashOperator task that runs 'echo Hello World'.

Apache Airflow

task = BashOperator(task_id='print_hello', bash_command='[1]')

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

Als -l

Bpwd

Cdate

Decho Hello World

Attempts:

3 left

💡 Hint

Common Mistakes

Using commands that do not print 'Hello World'.

Forgetting to put the command inside quotes.

The bash_command should be the shell command to run. Here, echo Hello World prints the message.

3fill in blank

hard

Fix the error in the BashOperator task by completing the missing argument.

Apache Airflow

task = BashOperator([1]='print_date', bash_command='date')

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

Adag

Bbash_command

Ctask_id

Downer

Attempts:

3 left

💡 Hint

Common Mistakes

Using bash_command instead of task_id as the first argument.

Omitting the task_id argument.

The task_id argument is required to name the task uniquely.

4fill in blank

hard

Fill both blanks to create a BashOperator that runs a command and assign it to a DAG.

Apache Airflow

task = BashOperator(task_id='list_files', bash_command='ls -l', [1]=[2])

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

Adag

Bmy_dag

Cdefault_args

Dargs

Attempts:

3 left

💡 Hint

Common Mistakes

Using default_args instead of dag.

Passing the wrong variable name for the DAG.

The dag argument assigns the task to the DAG object named my_dag.

5fill in blank

hard

Fill all three blanks to create a BashOperator with task_id, bash_command, and dag assigned.

Apache Airflow

task = BashOperator([1]='run_script', [2]='sh script.sh', [3]=my_dag)

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

Atask_id

Bbash_command

Cdag

Downer

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up argument names.

Forgetting to assign the task to the DAG.

The three main arguments are task_id, bash_command, and dag.

Practice

1. What is the main purpose of the BashOperator in Airflow?

easy

A. To run shell commands as part of a workflow task

B. To create Python functions for tasks

C. To schedule workflows at specific times

D. To monitor system resources during task execution

Solution

1. Step 1: Understand BashOperator's role

   BashOperator is designed to execute shell commands within Airflow tasks.

2. Step 2: Compare with other options

   Options B, C, and D describe other Airflow features but not BashOperator's main purpose.

3. Final Answer:

   To run shell commands as part of a workflow task -> Option A

4. Quick Check:

   BashOperator runs shell commands = A [OK]

Hint: BashOperator runs shell commands, not Python code [OK]

Common Mistakes:

• Confusing BashOperator with PythonOperator
• Thinking it schedules workflows
• Assuming it monitors system resources

2. Which of the following is the correct way to define a BashOperator task in Airflow?

easy

A. task = BashOperator(name='run_ls', command='ls -l')

B. task = BashOperator(id='run_ls', command='ls -l')

C. task = BashOperator(task_id='run_ls', bash_command='ls -l')

D. task = BashOperator(task='run_ls', shell_command='ls -l')

Solution

1. Step 1: Recall BashOperator parameters

   The correct parameters are task_id and bash_command.

2. Step 2: Match parameters with options

   Only task = BashOperator(task_id='run_ls', bash_command='ls -l') uses task_id and bash_command correctly.

3. Final Answer:

   task = BashOperator(task_id='run_ls', bash_command='ls -l') -> Option C

4. Quick Check:

   Correct parameters = D [OK]

Hint: Use task_id and bash_command keys exactly [OK]

Common Mistakes:

• Using 'id' instead of 'task_id'
• Using 'command' instead of 'bash_command'
• Mixing parameter names

3. Given this BashOperator task:

task = BashOperator(task_id='print_date', bash_command='date')

What will be the output when this task runs?

medium

A. An error because 'date' is not a valid command

B. The current date and time printed in the logs

C. No output because bash_command is empty

D. The string 'date' printed literally

Solution

1. Step 1: Understand the bash_command

   The command 'date' prints the current date and time in the shell.

2. Step 2: Predict task output

   When the task runs, it executes 'date' and logs the current date/time output.

3. Final Answer:

   The current date and time printed in the logs -> Option B

4. Quick Check:

   bash_command='date' outputs date/time = A [OK]

Hint: Commands run as in shell, so 'date' prints current date [OK]

Common Mistakes:

• Thinking 'date' is invalid command
• Expecting no output if command is given
• Confusing command string with literal output

4. What is wrong with this BashOperator task definition?

task = BashOperator(task_id='list_files', bash_command=ls -l)

medium

A. bash_command should be a string, not bare command

B. task_id cannot contain underscores

C. BashOperator requires a Python callable, not a string

D. Missing import statement for BashOperator

Solution

1. Step 1: Check bash_command syntax

   bash_command must be a string, so it should be quoted like 'ls -l'.

2. Step 2: Verify other options

   task_id can have underscores; BashOperator accepts strings; import is assumed outside task definition.

3. Final Answer:

   bash_command should be a string, not bare command -> Option A

4. Quick Check:

   bash_command needs quotes = B [OK]

Hint: Always quote bash_command string [OK]

Common Mistakes:

• Not quoting bash_command string
• Thinking task_id can't have underscores
• Confusing BashOperator with PythonOperator

5. You want to create a BashOperator task that lists all files in /tmp and saves the output to /tmp/file_list.txt. Which is the correct bash_command to use?

hard

A. bash_command='ls /tmp > file_list.txt'

B. bash_command='ls /tmp | /tmp/file_list.txt'

C. bash_command='ls /tmp >> /tmp/file_list.txt'

D. bash_command='ls /tmp > /tmp/file_list.txt'

Solution

1. Step 1: Understand output redirection

   The '>' operator redirects output to a file, overwriting it.

2. Step 2: Check file paths and command correctness

   bash_command='ls /tmp > /tmp/file_list.txt' correctly redirects 'ls /tmp' output to '/tmp/file_list.txt'. bash_command='ls /tmp >> /tmp/file_list.txt' appends instead of overwriting, which may be unwanted. bash_command='ls /tmp | /tmp/file_list.txt' uses pipe incorrectly. bash_command='ls /tmp > file_list.txt' writes to relative path, not /tmp.

3. Final Answer:

   bash_command='ls /tmp > /tmp/file_list.txt' -> Option D

4. Quick Check:

   Use '>' to redirect output to full path file [OK]

Hint: Use '>' for overwrite redirection with full file path [OK]

Common Mistakes:

• Using pipe '|' instead of redirection '>'
• Forgetting to specify full file path
• Using '>>' when overwrite is needed