Example method to find keywords and their preceding and following information in Linux logs

In daily work, we often need to view logs. For example, we can view logs in real time through the tail command, or we can view log information through commands such as cat .

But now we are going to discuss how to filter out the content we want from the log by keywords. There are many ways to do this. Today we will mainly learn about the cat command.

Assume that there is a log file hrun.log , and the query keyword is "new user":

View logs by keyword
cat hrun.log | grep "new user"

View the last 10 lines of logs according to keywords
cat hrun.log | grep "new user" -A 10

View the first 10 log lines by keyword
cat hrun.log | grep "new user" -B 10

View the 10 lines of logs before and after the keyword and display the line numbers
cat -n hrun.log | grep "New User" -C 10

View the first 50 lines of the log
cat hrun.log | head -n 50

View the last 50 lines of the log and display the line number
cat -n hrun.log | tail -n 50

illustrate:

• -A means after the keyword.
• -B means before the keyword.
• -C means before and after the keyword, Context

The above is all the knowledge points about finding keywords in Linux logs introduced this time. Thank you for your learning and support for 123WORDPRESS.COM.