The first is a detailed explanation of the lsof command:
lsof can only be executed with root privileges.
The lsof command can only be executed with root privileges. The
usage is as follows:
1. Display the process that opens the file abc.txt
lsof abc.txt
2. Show what program is currently occupied by port 22
lsof -i 22
3. Display the files that the abc process is now opening
lsof -c abc
4. Display the process status of the belonging gid
lsof -g gid
5. Display the files opened by the process in the specified directory, without traversing all subdirectories in the directory
lsof +d /usr/local/
6. Display the files opened by the process in the specified directory, and will traverse all subdirectories in the directory
lsof +D /usr/local/
7. Show processes using fd 4
lsof -d 4
8. Do not perform domain name resolution, it will be performed by default, which is relatively slow
lsof -n
9. View which files are opened by the process with process number 12
lsof -p 12
10. Let lsof execute repeatedly, default 15s refresh
lsof +|-r [t]
-r, lsof will execute forever until interrupted
+r, lsof will continue to execute until there is nothing to display
Example:
Check the current ftp connection: lsof -i [email protected]:ftp -r
11. List the size of the open file, if the size is 0, it is empty
lsof -s
12. List open files by UID
lsof -u username
13. Display the conditions of the eligible processes
Syntax: lsof -i[46] [protocol][@hostname|hostaddr][:service|port]
46 -- IPV4 or IPV6
protocol -- TCP or UDP
hostname -- Internet host name
hostaddr -- IP address
service -- service name in /etc/service (multiple choices)
port -- port number (multiple choices)
Example:
TCP:25 - TCP and port 25
@1.1.1.1 - IP 1.1.1.1
tcp @test.com - TCP protocol, ftp service
The following is a detailed explanation of the netstat command:
netstat can be run without root privileges
1. View the port number occupied by the process
netstat -anp
[root@nbatest ~]# netstat -anp | grep syslog //process name
udp 0 0 0.0.0.0:514 0.0.0.0:* 31483/syslogd
netstat -anp
[root@nbatest ~]# netstat -anp | grep 514 //port口
udp 0 0 0.0.0.0:514 0.0.0.0:* 31483/syslogd