此腳本將檢查 /var/log/messages 文件中的 “warning“、“error” 和 “critical”，如果發現任何有關的東西，就給指定電子郵件地址發郵件。

如果服務器有許多匹配的字符串，我們就不能經常運行這個可能填滿收件箱的腳本，我們可以在一天內運行一次。

為了解決這個問題，我讓腳本以不同的方式觸發電子郵件。

如果 /var/log/messages 文件中昨天的日志中找到任何給定字符串，則腳本將向給定的電子郵件地址發送電子郵件警報。

注意：你需要更改電子郵件地址，而不是我們的電子郵件地址。

# vi /opt/scripts/os-log-alert.sh

#!/bin/bash
#Set the variable which equal to zero
prev_count=0
 
count=$(grep -i "`date --date='yesterday' '+%b %e'`" /var/log/messages | egrep -wi 'warning|error|critical' | wc -l)
 
if [ "$prev_count" -lt "$count" ] ; then
    # Send a mail to given email id when errors found in log
    SUBJECT="WARNING: Errors found in log on "`date --date='yesterday' '+%b %e'`""
    # This is a temp file, which is created to store the email message.
    MESSAGE="/tmp/logs.txt"
    TO="2daygeek@gmail.com"
    echo "ATTENTION: Errors are found in /var/log/messages. Please Check with Linux admin." >> $MESSAGE
    echo  "Hostname: `hostname`" >> $MESSAGE
    echo -e "\n" >> $MESSAGE
    echo "+------------------------------------------------------------------------------------+" >> $MESSAGE
    echo "Error messages in the log file as below" >> $MESSAGE
    echo "+------------------------------------------------------------------------------------+" >> $MESSAGE
    grep -i "`date --date='yesterday' '+%b %e'`" /var/log/messages | awk '{ $3=""; print}' | egrep -wi 'warning|error|critical' >>  $MESSAGE
    mail -s "$SUBJECT" "$TO" < $MESSAGE
    #rm $MESSAGE
fi

為 os-log-alert.sh 文件設置可執行權限。

$ chmod +x /opt/scripts/os-log-alert.sh

最后添加一個 cron 任務來自動執行此操作。它將每天 7 點鐘運行。

# crontab -e

0 7 * * * /bin/bash /opt/scripts/os-log-alert.sh

注意：你將在每天 7 點收到昨天日志的電子郵件提醒。

輸出：你將收到類似下面的電子郵件提醒。

ATTENTION: Errors are found in /var/log/messages. Please Check with Linux admin.
 
+-----------------------------------------------------+
Error messages in the log file as below
+-----------------------------------------------------+
Jul  3 02:40:11 ns1 kernel: php-fpm[3175]: segfault at 299 ip 000055dfe7cc7e25 sp 00007ffd799d7d38 error 4 in php-fpm[55dfe7a89000+3a7000]
Jul  3 02:50:14 ns1 kernel: lmtp[8249]: segfault at 20 ip 00007f9cc05295e4 sp 00007ffc57bca1a0 error 4 in libdovecot-storage.so.0.0.0[7f9cc04df000+148000]
Jul  3 15:36:09 ns1 kernel: php-fpm[17846]: segfault at 299 ip 000055dfe7cc7e25 sp 00007ffd799d7d38 error 4 in php-fpm[55dfe7a89000+3a7000]
Jul  3 15:45:54 ns1 pure-ftpd: (?@5.188.62.5) [WARNING] Authentication failed for user [daygeek]
Jul  3 16:25:36 ns1 pure-ftpd: (?@104.140.148.58) [WARNING] Sorry, cleartext sessions and weak ciphers are not accepted on this server.#012Please reconnect using TLS security mechanisms.
Jul  3 16:44:20 ns1 kernel: php-fpm[8979]: segfault at 299 ip 000055dfe7cc7e25 sp 00007ffd799d7d38 error 4 in php-fpm[55dfe7a89000+3a7000]