RedHat Radius服务器Shell脚本邮件格式优化及重复发送问题求助

Let's break down your issues and fix the script while keeping all original functionality plus clean, readable email formatting:

The Root Causes of Your Problems #

1. mailx -E stopped working: Your formatted output always included separator lines and blank spaces, even when there were no new invalid user entries. This meant the email was never truly empty, so -E (which skips sending empty emails) had nothing to block.
2. Lost duplicate detection: You removed the core comm logic that compared new logs against previously sent entries, so the script kept trying to send content even when there was nothing new.

Fixed Script with Explanations #

#!/bin/bash
# Define configurable constants for easy maintenance
LOG_FILE="radius.log"
TRIGGER_PHRASE="Invalid user"
SENT_LOGS_TRACKER="myFile"
ALERT_EMAIL="myuser@email.com"
EMAIL_SUBJECT="Radius-Invalid-User Alert"

while :
do
    # Grab all current invalid user entries from the log
    current_alerts=$(grep "$TRIGGER_PHRASE" "$LOG_FILE")

    # Determine new, unsent entries
    if [ ! -e "$SENT_LOGS_TRACKER" ]; then
        # First run: no tracking file exists, use all current alerts
        new_alerts="$current_alerts"
    else
        # Compare current alerts against already sent ones, keep only new entries
        new_alerts=$(comm -23 <(echo "$current_alerts") "$SENT_LOGS_TRACKER")
    fi

    # Only process and send email if there are new alerts
    if [ -n "$new_alerts" ]; then
        # Update the tracking file with all current alerts to avoid duplicates next cycle
        echo "$current_alerts" > "$SENT_LOGS_TRACKER"

        # Generate clean, formatted email content from new alerts
        formatted_email=$(echo "$new_alerts" | awk '
        BEGIN {
            print "|-------------------------------------------------------------|"
            print " "
        }
        {
            # Parse fields from your log format (adjust indices if your log structure changes!)
            switch_name = $19
            port_number = $21
            mac_address = $11
            gsub(/[()]/, "", mac_address)  # Clean up parentheses around MAC

            # Build formatted block for each alert
            print " Switch: " switch_name
            print " "
            print "|-------------------------------------------------------------|"
            print " "
            print " Port-Nr: " port_number
            print " "
            print "|-------------------------------------------------------------|"
            print " "
            print " MAC-Address: " mac_address
            print " "
            print "|-------------------------------------------------------------|"
            print " "
        }')

        # Send the formatted email - -E will work because we only run this when content exists
        echo "$formatted_email" | mailx -E -s "$EMAIL_SUBJECT" "$ALERT_EMAIL"
    fi

    # Adjust sleep time to reduce system load (1 second is very frequent; 60 seconds is more reasonable)
    sleep 60
done

Key Improvements #

• Restored duplicate detection: The comm -23 logic is retained to ensure only new invalid user attempts trigger an email.
• Fixed mailx -E behavior: We only generate and send email when there are actual new alerts, so the content is never empty when we reach the mailx command.
• Better formatting handling: Uses awk to loop through every new alert entry (not just the last one in the file) and clean up fields like the MAC address.
• Maintainable structure: Constants at the top make it easy to update log paths, email addresses, or sleep intervals without digging into the script logic.

Important Notes #

• Double-check the field indices ($19, $21, $11) in the awk block. If your Radius log format changes, you'll need to adjust these to match the actual position of switch name, port, and MAC address in your logs.
• Consider increasing the sleep value from 1 second to 60 (or longer) to reduce unnecessary system resource usage.

内容的提问来源于stack exchange，提问作者averagejoe