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How to understand the lsof command on the Linux operating system, I believe that many inexperienced people do not know what to do. Therefore, this paper summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

The full name of lsof is list opened files, which lists the files that have been opened in the system. As we all know, in a linux environment, everything is a file, a device is a file, a directory is a file, and even a sockets is a file. Therefore, the good use of lsof commands is very helpful to day-to-day linux management. Only ordinary root users can execute lsof commands. Ordinary users can see the / usr/sbin/lsof command, but ordinary users' execution will display "permission denied".

Let me summarize the usage of the lsof instruction:

Lsof abc.txt shows the process of opening the file abc.txt

Lsof-I: 22 know what program port 22 is running now

Lsof-c abc displays the files now opened by the abc process

Lsof-g gid shows the process that belongs to the gid

Lsof + d / usr/local/ displays the files opened by the process in the directory

Lsof + D / usr/local/ is the same as above, but will search the directory under the directory for a long time.

Lsof-d 4 shows processes using fd 4

Lsof-I is used to display eligible processes.

Syntax: lsof-I [46] [protocol] [@ hostname | hostaddr] [: service | port]

46-- > IPv4 or IPv6

Protocol-- > TCP or UDP

Hostname-- > Internet hostname

Hostaddr-- > IPv4 location

Service name in service-- > / etc/service (can be more than one)

Port-- > port number (can be more than one)

Example: TCP:25-TCP and port 25

@ 1.2.3.4-Internet IPv4 host address 1.2.3.4

Tcp@o.ks.edu.tw:ftp-TCP protocol host.ks.edu.tw service name:ftp

Lsof-n does not convert IP to hostname. By default, the-n parameter is not added.

Example: lsof-I tcp@o.ks.edu.tw:ftp-n

Lsof-p 12 to see which files are opened by the process with process number 12

Lsof + |-r [t] controls the repeated execution of lsof. Default is 15s refresh.

-rrecoery lsof will be executed forever until the interrupt signal is received

+ rforce lsof will be executed until no files are displayed

Example: constantly check the current ftp connection: lsof-I tcp@o.ks.edu.tw:ftp-r

Lsof-s lists the size of the open file, leaving it blank if there is no size

Lsof-u username lists open files in UID

Only ordinary root users can execute lsof commands. Ordinary users can see the / usr/sbin/lsof command, but ordinary users' execution will display "permission denied".

Let me summarize the usage of the lsof instruction:

Lsof abc.txt shows the process of opening the file abc.txt

Lsof-I: 22 know what program port 22 is running now

Lsof-c abc displays the files now opened by the abc process

Lsof-g gid shows the process that belongs to the gid

Lsof + d / usr/local/ displays the files opened by the process in the directory

Lsof + D / usr/local/ is the same as above, but will search the directory under the directory for a long time.

Lsof-d 4 shows processes using fd 4

Lsof-I is used to display eligible processes.

Syntax: lsof-I [46] [protocol] [@ hostname | hostaddr] [: service | port]

46-- > IPv4 or IPv6

Protocol-- > TCP or UDP

Hostname-- > Internet hostname

Hostaddr-- > IPv4 location

Service name in service-- > / etc/service (can be more than one)

Port-- > port number (can be more than one)

Example: TCP:25-TCP and port 25

@ 1.2.3.4-Internet IPv4 host address 1.2.3.4

Tcp@o.ks.edu.tw:ftp-TCP protocol host.ks.edu.tw service name:ftp

Lsof-n does not convert IP to hostname. By default, the-n parameter is not added.

Example: lsof-I tcp@o.ks.edu.tw:ftp-n

Lsof-p 12 to see which files are opened by the process with process number 12

Lsof + |-r [t] controls the repeated execution of lsof. Default is 15s refresh.

-rrecoery lsof will be executed forever until the interrupt signal is received

+ rforce lsof will be executed until no files are displayed

Example: constantly check the current ftp connection: lsof-I tcp@o.ks.edu.tw:ftp-r

Lsof-s lists the size of the open file, leaving it blank if there is no size

Lsof-u username lists open files in UID

Lsof-I tcp:22 to check the progress of port 22

After reading the above, have you mastered how to understand the lsof command on the Linux operating system? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

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