UUCP knowledge in Unix

UUCP knowledge in Unix
GuideThere are many things worth learning about the Unix operating system. Here we will mainly introduce the uucp in the Unix operating system. Let's take a look! The UUCP system is a set of programs that complete file transmission, execute commands between systems, maintain statistics on system usage, and protect security.

UUCP is the most widely used network utility system for two reasons:

* First, UUCP is the only standard network system available for various Unix operating system versions.

* Second, UUCP is the cheapest network system. you only need a cable to connect two systems, and then you can establish UUCP. if you want to transmit data between two systems that are several hundred or thousands of kilometers apart, you need two modem with the dialing function.

1 Unix UUCP command

UUCP is one of the UCP commands. This command is used for file transmission between two systems. The uucp command format is similar to the cp command format, but UCP allows users to copy files between systems. The general format of the command is as follows:

Source_file is usually a Unix operating system file, but it does not have to be. destination_file is usually a file or directory of another system. The format of destination_file specified is:

Uucp provides the system administrator with an option to restrict the transfer of uucp files to and from Unix operating systems to the/usr/spool/uucppublic directory structure. if you tell uucp to store the transmitted file in another directory, the system will return one:

Uucp allows simplified symbols ~ Replace/usr/spool/uucppublic/. For example:

Sometimes uucp can be used to copy files from another system to the Unix operating system. If the file to be passed into the system is specified as the source file, use system! File, for example:

If the directory for file transfer is restricted on the remote machine, the previous command cannot be copied to the file. the safest way to copy files to the system is to transfer files in both systems through the uucppublic directory.

2 uux command

Uux commands can be used to execute commands on another Unix operating system, which is called "Remote Command Line ". uux is most commonly used to send emails between systems and execute uux internally. typical uux requests are as follows:

This command is used to orchestrate the file listing format and then connect to the remote1 printer pr1. uux's option "-" enables uux to establish the standard input device of this command as a standard input device for remote commands. when only one of several systems is connected to a printer, uux usually prints files.

Of course, you must strictly restrict remote command reception to protect system security. For example, the system should not allow users on other systems to run the following commands:

This command transfers the/etc/passwd file to the outside of the Unix operating system. Generally, only a few commands can be executed. rmail is a restricted mail program. It is often one of the commands that can be executed through uux. the netnews pseudo-Offline commands restricted by rnews can also be executed on the system that runs netnews, and lp can be run on the system that provides printing devices.

3 uucico Program

Uucp and uux commands do not actually call another system and send files and execute commands. Instead, they queue user requests and start uucico programs. uucico completes the actual communication work. it calls other systems, logs on, transfers data, or requests remote command execution. if the telephone line is busy or other Unix operating systems have been shut down, the transmission request is still in the queue, and the subsequent function of uucico is usually to send these transfer requests after cron completes.

Uucico sends and receives data. in the/etc/passwd file of the system, uucico of other systems is logged on to the portal of the system. The default shell specified in this portal is uucico. therefore, when other systems call the system, they directly talk to uucico.

4 uuxqt Program

When another uucico calls a remote command execution request from the Unix operating system, the uucico of the system queues the request and starts the uuxqt program to execute the remote command request before exiting.

From: http://www.linuxeden.com/html/unix/20130206/135431.html

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