How to implement real-time log analysis in Linux?

With the rapid development of the Internet, log analysis has increasingly become an important task, helping us understand the operating status of the system, troubleshooting, and security audits. In the Linux environment, the need for real-time log analysis is becoming more and more important. This article will introduce how to implement real-time log analysis in Linux and provide code examples.

1. View the log file
First, we need to view the log file to be analyzed. Log files are usually located in the /var/log directory of the Linux system. Commonly used log files are: /var/log/syslog (system log), /var/log/auth.log (authentication log), /var/log/kern .log (kernel log), etc. By using the command line tool tail, we can view the contents of the log file in real time.

For example, the following command can view the system log in real time:
tail -f /var/log/syslog

2. Filter keywords
In actual log analysis, We usually only focus on log information related to specific keywords. In order to filter keywords in real time, we can use the command line tool grep.

For example, the following command can filter the system logs containing the "error" keyword in real time:
tail -f /var/log/syslog | grep "error"

三, Statistical log information
In addition to filtering keywords, we may also need to perform statistics on log information, such as calculating the frequency of a certain keyword. In order to achieve this function, we can use the command line tool awk.

For example, the following command can count the frequency of the "error" keyword in the system log in real time:
tail -f /var/log/syslog | grep "error" | awk '{count[$0 ] } END {for (line in count) print line": "count[line]" times"}'

4. Automated analysis
In order to achieve automated log analysis, we can use shell scripts in combination and cron scheduled tasks. The following is an example shell script for real-time statistics of the number of "error" keywords that appear in the system log per minute:

!/bin/bash

LOG_FILE="/var/ log/syslog"

Clear the log

echo "" > ${LOG_FILE}_error.log

Scheduled task, run once every minute

while [ true ]
do

# 统计每分钟的错误次数
count=$(tail -n 100 ${LOG_FILE} | grep -c "error")

# 将统计结果输出到日志文件中
echo "$(date +"%Y-%m-%d %H:%M:%S"): ${count}" >> ${LOG_FILE}_error.log

# 休眠60秒
sleep 60

done

Save the above code into a script file (such as log_analysis.sh) and add executable permissions.

Then, we can use cron scheduled tasks to execute the script every minute:

• • • • ##/path/to/log_analysis.sh >/dev/null 2>&1
##Through the above configuration, the system will automatically execute the log_analysis.sh script every minute, count the number of "error" keywords that appear in the system log every minute, and output the results to the /var/log/syslog_error.log file middle.

Through the above steps, we can achieve real-time log analysis in Linux. Using the command line tools tail, grep, and awk, we can view and filter log information in real time; and by combining shell scripts and cron scheduled tasks, we can achieve automated log analysis. In practical applications, the code can be modified and optimized according to needs to meet specific analysis needs.

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