Today, the instructor asked to use linux to view the log. Here, I first learned about the linux of the ubuntu kernel, and now review the statement to view the log.
Linux view log command
1. tail
View real-time logs
tail -f
You can add grep keywords to filter log keywords
tail -F dpkg.log | grep --line-buffer '关键字'
ctrl + c to end log printing
When the file is relatively large, get the last 1000 rows of data in the log
tail -n 1000 文件名 > 本地文件
If you want to monitor logs continuously
tail -f 文件名
Note here: If you use the vi command, it cannot be monitored
Reason: The principle of vi is to delete the file first and then create it.
If you want to monitor it, you can use the big F
tail -f 文件名
Two, head
Look at the first 100 lines of the log
head -100 文件名
Three, cat
View log files directly
cat 文件名
Four, more
more 文件名
space to scroll down
b key to scroll up
Starting from 1000 lines, turn 20 lines each time
more +1000 -20 文件名
qquit
Five, view
view 文件名
Then you can use the following command to search
/关键字
5.1 Search from top to bottom
Press n to find the next one
5.2 Search from bottom to top
Enter the following command to come to the last line
:$
then type
/关键字
At this time, press n to search up.
5.3 Exit
:q
6. Search
6.1 Fuzzy search
If you only know a certain keyword in the log, now you want to search globally
grep ‘关键字’ *.log
6.2 File location
I only know a certain keyword in the log log, but I don't know where the file is
find . -name "*.log" | xargs grep -r "关键字"
7. Frequently asked questions
7.1 The newly installed ubuntu does not set the root password
sudo passwd root
First enter the password of the currently logged in user, then enter the password of the root user twice
and then switch to the root user
su root
7.2 Command not found
Generally, there will be prompts, just follow the prompts
sudo apt install tree
8. Other common commands
8.1 echo input to the file
echo "文字" >> 文件名
8.2 pwd
pwd:print working directory
pwd
8.3 ls
list
view directory
ls
8.4 cd
change directory
cd /var/log
