Script: Email notifications when machine is free

outline¶

login to free SMTP server(qq, google) to send email to others.

send email using command line¶

check ping mail.ustc.edu.cn
MUST : set gmail open to support SMTP and apppassword
or config qq email

IMAP, POP3 or SMTP¶

mailutils¶

According to ref1.

# install ca-certificates
# After new a google accounts, 
# config according to ref1

sudo apt-get install mailutils
$ echo "Hello world" | mail -s "Test" [email protected]

send but the same, more crazy thing is the -v and -d flag is not supported. and --debug-level=trace0 isn't recognized. many same question in StackOverflow

sudo tail -n 30 /var/log/mail.log or mail.error show more info.

ssmtp¶

We try ref2 ssmtp, sudo vim /etc/ssmtp/ssmtp.conf

TLS_CA_FILE=/etc/pki/tls/certs/ca-bundle.crt
root=[email protected]
mailhub=smtp.gmail.com:587
rewriteDomain=gmail.com
AuthUser=shaojieemail
AuthPass={apppassword}
FromLineOverride=YES
UseSTARTTLS=Yes
UseTLS=YES
hostname=snode6

The config get work but not well configed, e.g., TLS_CA_FILE

sending a email using gmail took about 13 mins.

$ ssmtp 943648187@qq.com < mail.txt
......
[->] Received: by snode6 (sSMTP sendmail emulation); Wed, 06 Sep 2023 15:42:05 +0800
[->] From: "Shaojie Tan" <[email protected]>
[->] Date: Wed, 06 Sep 2023 15:42:05 +0800
[->] test server email sending
[->]
[->] .
[<-] 250 2.0.0 OK  1693986323 5-20020a17090a1a4500b0026b4ca7f62csm11149314pjl.39 - gsmtp
[->] QUIT
[<-] 221 2.0.0 closing connection 5-20020a17090a1a4500b0026b4ca7f62csm11149314pjl.39 - gsmtp

sendmail¶

$ sendmail [email protected] < mail.txt
sendmail: Authorization failed (535 5.7.8  https://support.google.com/mail/?p=BadCredentials e7-20020a170902b78700b001c0c79b386esm8725297pls.95 - gsmtp)

get to work after well config gmail setting.

Speed Compare¶

command	snode6 time(mins)	icarus1
mail	4	1s
ssmtp	13
sendmail	6

send email by python¶

ref using QQ apppassword and python.

email notifications¶

Create a Bash Script: Create a Bash script that checks the CPU usage and sends an email if it's below 30%. For example, create a file named cpu_check.sh:

#!/bin/bash

# Get CPU usage percentage
cpu_usage=$(top -b -n 1 | grep '%Cpu(s):' | awk '{print $2}' | cut -d'.' -f1)
echo "cpu_usage : ${cpu_usage} on $(hostname)"
# Check if CPU usage is below 30%
if [ "$cpu_usage" -lt 30 ]; then
   echo "beyond threshold : ${cpu_usage} on "
    # Send an email
    echo "CPU usage is ${cpu_usage} below 30% on $(hostname)" | mail -s "Low CPU Usage Alert on $(hostname)" [email protected]
fi

Make the script executable:

chmod +x cpu_check.sh

Modify [email protected] with your actual email address.

Schedule the Script: Use the cron scheduler to run the script at regular intervals. Edit your crontab by running:

crontab -e

Add an entry to run the script, for example, every 5 minutes:

*/5 * * * * /staff/shaojiemike/test/cpu_check.sh >> /staff/shaojiemike/test/cpu_check.log
# Run every 15 minutes during working hours (9 am to 7 pm)
*/15 9-19 * * * /path/to/your/script.sh

Replace /path/to/cpu_check.sh with the actual path to your Bash script.

Save and Exit: Save the crontab file and exit the text editor.

Now, the script will run every 5 minutes (adjust the cron schedule as needed) and send an email notification if the CPU usage is below 50%. You should receive an email when the condition is met.

Please note that this is a basic example, and you can modify the script to include more details or customize the notification further as needed. Additionally, ensure that your server is configured to send emails; you may need to configure SMTP settings for the mail or sendmail command to work correctly.

需要进一步的研究学习¶

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遇到的问题¶

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开题缘由、总结、反思、吐槽~~¶

参考文献¶

上面回答部分来自ChatGPT-3.5，没有进行正确性的交叉校验。

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