It is determined by the difference between a hyphen (-) and two hyphens (-) before the command parameters in the Linux Command Line.

Before explaining these differences, let's take a look at the background knowledge about Linux. This requires you to carefully read these differences and have a deeper understanding of Linux.

About the System V and BSD styles and Their Relationship with Linux:

1. System V and BSD are two different departments out of the at&t lab. systemv is a UNIX commercial standard and BSD is a UNIX standard Berkeley.

2. Because Linux is a Linux system redeveloped by Linus Torvalds with Unix architecture, it still follows the process style of the two major UNIX systems, actually, Linus Torvalds only develops kernel, and the software still comes from the GNU and GPL organizations.

 

Currently, only slackware is the only BSD version in the Linux release. Others are FreeBSD, NetBSD, and OpenBSD, which follow the "GPL specification 」. In the commercial version of UNIX and most Linux distributions, the systemv-style init may have a copyright dispute 』. Linux represents almost a majority of releases, such as RedHat, Suse, DV, magiclinux, and Debian. UNIX represents Aix, Irix, solars, and HP-UX.

After introducing the background knowledge, let's take a look at the usage of these command parameters:

1. Some commands in Linux use LS-A (the front of the parameter) like this );

2. Some commands use CP -- Help (the first two parameters) in this way );

3. Use tar-xzvf (a horizontal line exists before the parameter );

4. In this case, tar xzvf is used (the parameter is not horizontal ).

 

The differences in command usage are explained one by one:

First, the parameter follows a horizontal description of the character format.

The second type: two horizontal parameters are followed by the word form.

Third: The System V style is the front of the parameter.

Fourth, the BSD style is not horizontal before the parameter.

 

Other differences between System V and BSD:

During system startup, the last step of the kernel is to call the INIT program. There are two methods for executing the INIT program: System V and BSD.
In the system v style, init calls/etc/inittab and BSD calls/etc/rc for the same purpose. They all execute a series of programs based on runlevel.

 

Conclusion: A question brings so much background knowledge that it makes progress only when there is a problem.