Logging framework in Bash Scripting - Mini Project: Build & Apply

Logging Framework in Bash

📖 Scenario: You are creating a simple logging framework in a Bash script. This will help you track messages with different levels like INFO, WARNING, and ERROR in your scripts.

🎯 Goal: Build a Bash script that defines a log function to print messages with a timestamp and log level. You will also set a log level threshold to control which messages get printed.

📋 What You'll Learn

Create a variable to hold the current log level threshold.

Define a function called log that takes two arguments: log level and message.

The function should print the message only if the message's log level is equal or higher than the threshold.

Print log messages with a timestamp and the log level in uppercase.

💡 Why This Matters

🌍 Real World

Logging is essential in scripts to track what happens and find problems quickly.

💼 Career

DevOps engineers and system administrators use logging frameworks to monitor and debug automation scripts.

1

Set up log level variables

Create three variables called LOG_LEVEL_INFO, LOG_LEVEL_WARNING, and LOG_LEVEL_ERROR with values 1, 2, and 3 respectively.

Bash Scripting

# Your code here

Need a hint?

Use simple variable assignments like VAR=value.

2

Set the current log level threshold

Create a variable called CURRENT_LOG_LEVEL and set it to LOG_LEVEL_WARNING.

Bash Scripting

LOG_LEVEL_INFO=1
LOG_LEVEL_WARNING=2
LOG_LEVEL_ERROR=3
# Your code here

Need a hint?

Assign CURRENT_LOG_LEVEL using the existing variable LOG_LEVEL_WARNING.

3

Define the log function

Write a function called log that takes two arguments: level and message. Inside the function, check if level is greater than or equal to CURRENT_LOG_LEVEL. If yes, print the message with the current timestamp and the log level in uppercase. Use date +"%Y-%m-%d %H:%M:%S" for the timestamp.

Bash Scripting

LOG_LEVEL_INFO=1
LOG_LEVEL_WARNING=2
LOG_LEVEL_ERROR=3
CURRENT_LOG_LEVEL=$LOG_LEVEL_WARNING
# Your code here

Need a hint?

Use if to compare levels, case to get level name, and echo to print.

4

Test the logging function

Call the log function three times with these arguments:
1. LOG_LEVEL_INFO, "This is an info message"
2. LOG_LEVEL_WARNING, "This is a warning message"
3. LOG_LEVEL_ERROR, "This is an error message"
Print the output of these calls.

Bash Scripting

LOG_LEVEL_INFO=1
LOG_LEVEL_WARNING=2
LOG_LEVEL_ERROR=3
CURRENT_LOG_LEVEL=$LOG_LEVEL_WARNING

log() {
    local level=$1
    local message=$2
    if [ "$level" -ge "$CURRENT_LOG_LEVEL" ]; then
        local timestamp=$(date +"%Y-%m-%d %H:%M:%S")
        local level_name=""
        case $level in
            $LOG_LEVEL_INFO) level_name="INFO" ;;
            $LOG_LEVEL_WARNING) level_name="WARNING" ;;
            $LOG_LEVEL_ERROR) level_name="ERROR" ;;
            *) level_name="UNKNOWN" ;;
        esac
        echo "$timestamp [$level_name] $message"
    fi
}
# Your code here

Need a hint?

Only messages with level WARNING and ERROR should print because the threshold is WARNING.