How to Install and Configure Mailx for Automated Log Monitoring on Linux

The article explains a practical solution for monitoring Linux server logs and sending email alerts when specific keywords appear.

1. Install Mailx

Download the Mailx source package and extract it:

tar -jxf mailx-12.4.tar.bz2 -C /usr/src/ && cd /usr/src/mailx-12.4/

Compile and install: make install UCBINSTALL=/usr/bin/install If compilation fails, apply the provided patch:

patch -p0 < mailx-12.4-openssl_1.0.0_build_fix-1.patch

Re‑run the install command after patching.

2. Verify Installation

Check the installed version:

mailx -V

3. Configure Mailx

Edit /etc/nail.rc and add the following lines at the end (replace placeholders with your actual values):

set [email protected]
set smtp=smtp.example.com
set smtp-auth-user=your_user
set smtp-auth-password=your_password
set smtp-auth=login

Save the file; the configuration is now ready.

4. Test Email Sending

Send a test message from the command line:

echo '邮件正文' | mailx -v -s "邮件标题" [email protected]

If the command succeeds, Mailx is correctly configured.

5. Develop Keyword Monitoring Scripts

Two shell scripts are used:

CheckLogs.sh – monitors a log file, remembers the last read line, and scans new lines for configured keywords.

SendMail.sh – sends an email; can be customized for subject, body, and recipients.

A configuration directory ( conf) holds a file named chklist that lists the keywords to watch for.

When CheckLogs.sh runs for the first time, it records the current line count. Subsequent runs read only the newly appended lines; if any of the keywords appear, the script invokes SendMail.sh to issue an alert.

Testing steps include inserting a test keyword (e.g., error) into the monitored log, running the script, and confirming that the keyword is captured and an email is sent. The article also demonstrates monitoring multiple keywords and controlling the check frequency.

After completing these tests, the log‑monitoring and email‑alert system is fully operational.