Lock files for single instance in Bash Scripting - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a lock file before running the script.

Bash Scripting

lockfile=/tmp/mylockfile.lock
if [ -e [1] ]; then
  echo "Script is already running."
  exit 1
fi

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

A/tmp/mylockfile.lock

Blockfile

C/var/lock/myscript.lock

D/tmp/lockfile

Attempts:

3 left

💡 Hint

Common Mistakes

Using the variable name 'lockfile' without the '$' sign.

Checking a wrong file path.

The script checks if the lock file path stored in the variable 'lockfile' exists. The correct path is '/tmp/mylockfile.lock'.

2fill in blank

medium

Complete the code to create the lock file after confirming it does not exist.

Bash Scripting

touch [1]

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

A/var/lock/myscript.lock

B$lockfile

C/tmp/mylockfile.lock

Dlockfile

Attempts:

3 left

💡 Hint

Common Mistakes

Using the variable name without '$' so the file named 'lockfile' is created.

Using a different file path than the one stored in 'lockfile'.

To create the lock file, use the variable 'lockfile' with a '$' to get its value.

3fill in blank

hard

Fix the error in the code to remove the lock file after the script finishes.

Bash Scripting

rm [1]

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

Alockfile

B/tmp/mylockfile.lock

C$lockfile

D/var/lock/myscript.lock

Attempts:

3 left

💡 Hint

Common Mistakes

Removing a file named literally 'lockfile' instead of the path stored in the variable.

Removing the wrong file path.

To remove the lock file, use '$lockfile' to refer to the variable's value.

4fill in blank

hard

Fill both blanks to create a safe lock file check and creation.

Bash Scripting

if [ -e [1] ]; then
  echo "Already running"
  exit 1
fi
[2] [1]

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

A$lockfile

Blockfile

Ctouch

Drm

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'lockfile' without '$' in the test condition.

Using 'rm' instead of 'touch' to create the file.

Check if the file at '$lockfile' exists, then create it with 'touch $lockfile'.

5fill in blank

hard

Fill all three blanks to create a dictionary of running scripts with their lock files and check if a script is running.

Bash Scripting

declare -A locks=([[1]]=[2])
script="myscript"
if [ -e "${locks[$ [3] ]}" ]; then
  echo "$script is already running."
  exit 1
fi

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

A"myscript"

B"/tmp/myscript.lock"

Cscript

D"myotherscript"

Attempts:

3 left

💡 Hint

Common Mistakes

Using variable names without quotes in the dictionary.

Checking the wrong key in the dictionary.

The dictionary 'locks' maps script names to lock file paths. Use 'myscript' as key and its lock file path. Then check if the lock file for the current script exists.