China DOS Union

As the question says: I saw the statement "ping -n 1 127.1>nul" in several batch files. What does "ping -n 1 127.1>nul" mean? Can the experts explain it?

Start/Run hh ntcmds.chm::/ntcmds.htm

It mainly plays a role in delay, and there seems to be nothing else. 127.1 is the loopback address of this machine, which is equivalent to 127.0.0.1. Not only can 127.0.0.1 be written in the form of 127.1, but other types of IP addresses can also be, for example: 61.0.0.28 can also be written in the form of 61.28.

Oh, I see. Thank you, two friends!

### About `ping -n 1 127.1>nul:`

1. `ping` is a network command to test network connectivity. The parameter "-n 1" means sending only one ICMPS packet to test network connectivity.

2. `127.1` represents the local reserved IP address, which is actually 127.0.0.1. Pinging 127.1 means pinging 127.0.0.1, which can test whether the network card and TCP/IP protocol are installed and working properly.

3. `>nul` means redirecting the screen display information generated by the command (>) to the null device (nul), so that the execution result of the ping command is not displayed on the screen. If you want to block error messages, you can use `>nul 2>nul` to block all screen output.

If you want to block error messages, you can use ">nul 2>nul" to block all screen output.

This sentence is not very understandable -_-

Re: xyxFlysky
　　The ">nul 2>nul" can block all screen output. Here's the understanding:

　　Suppose you execute a command but don't want to see the execution result on the screen. You can use " >nul" to block the output of the command on the screen. But some commands may produce error messages, and even using ">nul" can't block the information they generate. So adding " 2>nul" after it, that is, " >nul 2>nul", in this way, whether the command runs correctly or not, you won't see the screen display generated by this command.

　　Let's take a simple example.

　　The "dir" command can display the file and folder list of the current directory. At this time, if you use "dir >nul", you won't see the screen output of the dir command. Then what will happen if you type "dirr"? At this time, it will display " 'dirr' is not an internal command, nor an external command, nor a batch file." Then you may use "dirr >nul" to block this error message, but I tell you, your guess is wrong because the error message " 'dirr' is not an internal command, nor an external command, nor a batch file." will still appear. At this time, if you use "dirr >nul 2>nul", you won't see the above error message on the screen. I don't know if you understand it now.

　　If you want to know more about the explanation of nul, you can search in the forum. You can find the detailed and wonderful explanation of the usage of nul by brother willsort.


[ Last edited by lxmxn on 2006-10-26 at 12:33 AM ]

Brother lxmxn, your explanation is very detailed and has helped me understand the puzzles that I couldn't figure out before. I really appreciate your patient guidance, thank you!

The example is really vivid, appreciate it~ :)

Brother lxmxn has a very cool avatar, and he himself is very patient. Thumbs up!

If you understand Linux, it's easy to understand the concept of the null device

Ping -n 1 127.1>nul How to use this? I just want a similar usage. That is, executing ping -n 1 127.1>nul it will have no information. Then why execute it?

[ Last edited by yangzhiyi on 2006-10-29 at 12:51 AM ]

Crazy, the step-by-step execution of batch commands still needs to use delays. Usually, it's done with jumps. Using ping -n 1 127.1>nul for delays is even crazier.