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sources/tech/20190705 Bash Script to Monitor Messages Log (Warning, Error and Critical) on Linux.md
128 lines
5.0 KiB
Markdown
128 lines
5.0 KiB
Markdown
[#]: collector: (lujun9972)
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[#]: translator: ( )
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[#]: reviewer: ( )
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[#]: publisher: ( )
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[#]: url: ( )
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[#]: subject: (Bash Script to Monitor Messages Log (Warning, Error and Critical) on Linux)
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[#]: via: (https://www.2daygeek.com/linux-bash-script-to-monitor-messages-log-warning-error-critical-send-email/)
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[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
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Bash Script to Monitor Messages Log (Warning, Error and Critical) on Linux
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======
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There are many open source monitoring tools are currently available in market to monitor Linux systems performance.
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It will send an email alert when the system reaches the specified threshold limit.
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It monitors everything such as CPU utilization, Memory utilization, swap utilization, disk space utilization and much more.
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If you only have few systems and want to monitor them then writing a small shell script can make your task very easy.
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In this tutorial we have added a shell script to monitor Messages Log on Linux system.
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We had added many useful shell scripts in the past. If you want to check those, navigate to the below link.
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* **[How to automate day to day activities using shell scripts?][1]**
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This script will check **“warning, error and critical”** in the `/var/log/messages` file and trigger a mail to given email id, if it’s found anything related it.
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We can’t run this script frequently that may fill up your inbox if the server has many matching strings, instead we can run once in a day.
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To overcome this issue, i made the script to trigger an email in a different manner.
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If any given strings are found in the **“/var/log/messages”** file for yesterday’s date then the script will send an email alert to given email id.
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**Note:** You need to change the email id instead of ours. Also, you can change the Memory utilization threshold value as per your requirement.
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```
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# vi /opt/scripts/os-log-alert.sh
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#!/bin/bash
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#Set the variable which equal to zero
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prev_count=0
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count=$(grep -i "`date --date='yesterday' '+%b %e'`" /var/log/messages | egrep -wi 'warning|error|critical' | wc -l)
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if [ "$prev_count" -lt "$count" ] ; then
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# Send a mail to given email id when errors found in log
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SUBJECT="WARNING: Errors found in log on "`date --date='yesterday' '+%b %e'`""
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# This is a temp file, which is created to store the email message.
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MESSAGE="/tmp/logs.txt"
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TO="[email protected]"
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echo "ATTENTION: Errors are found in /var/log/messages. Please Check with Linux admin." >> $MESSAGE
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echo "Hostname: `hostname`" >> $MESSAGE
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echo -e "\n" >> $MESSAGE
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echo "+------------------------------------------------------------------------------------+" >> $MESSAGE
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echo "Error messages in the log file as below" >> $MESSAGE
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echo "+------------------------------------------------------------------------------------+" >> $MESSAGE
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grep -i "`date --date='yesterday' '+%b %e'`" /var/log/messages | awk '{ $3=""; print}' | egrep -wi 'warning|error|critical' >> $MESSAGE
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mail -s "$SUBJECT" "$TO" < $MESSAGE
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#rm $MESSAGE
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fi
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```
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Set an executable permission to `os-log-alert.sh` file.
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```
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$ chmod +x /opt/scripts/os-log-alert.sh
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```
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Finally add a cronjob to automate this. It will run everyday at 7'o clock.
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```
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# crontab -e
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0 7 * * * /bin/bash /opt/scripts/os-log-alert.sh
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```
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**Note:** You will be getting an email alert everyday at 7 o'clock, which is for yesterday's log.
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**Output:** You will be getting an email alert similar to below.
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```
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ATTENTION: Errors are found in /var/log/messages. Please Check with Linux admin.
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+-----------------------------------------------------+
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Error messages in the log file as below
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+-----------------------------------------------------+
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Jul 3 02:40:11 ns1 kernel: php-fpm[3175]: segfault at 299 ip 000055dfe7cc7e25 sp 00007ffd799d7d38 error 4 in php-fpm[55dfe7a89000+3a7000]
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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]
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Jul 3 15:36:09 ns1 kernel: php-fpm[17846]: segfault at 299 ip 000055dfe7cc7e25 sp 00007ffd799d7d38 error 4 in php-fpm[55dfe7a89000+3a7000]
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Jul 3 15:45:54 ns1 pure-ftpd: ([email protected]) [WARNING] Authentication failed for user [daygeek]
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Jul 3 16:25:36 ns1 pure-ftpd: ([email protected]) [WARNING] Sorry, cleartext sessions and weak ciphers are not accepted on this server.#012Please reconnect using TLS security mechanisms.
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Jul 3 16:44:20 ns1 kernel: php-fpm[8979]: segfault at 299 ip 000055dfe7cc7e25 sp 00007ffd799d7d38 error 4 in php-fpm[55dfe7a89000+3a7000]
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```
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--------------------------------------------------------------------------------
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via: https://www.2daygeek.com/linux-bash-script-to-monitor-messages-log-warning-error-critical-send-email/
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作者：[Magesh Maruthamuthu][a]
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选题：[lujun9972][b]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://www.2daygeek.com/author/magesh/
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[b]: https://github.com/lujun9972
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[1]: https://www.2daygeek.com/category/shell-script/
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