What's up with this Windows batch file?

[Ichinisan]

I know perfectly well how to restart explorer.exe via the command line. I've actually done it a lot over the past few weeks (since Systernals Process Monitor somehow trashed itself *and* the Windows Task Manager). It's long past time to reinstall Windows on my work computer and jump from XP to 7 🙂

I don't remember what I was looking for when I came across instructions to create this batch file:

@echo off
color 0B
echo JumpStart! v0.1 by Scotch
echo.
echo Your desktop is being restored, Please wait. . .
ping -n 5 127.0.0.1 > NUL 2>&1
echo Killing process Explorer.exe. . .
taskkill /f /im explorer.exe
cls
echo Success!
echo.
echo Your desktop is now loading. . .
ping -n 5 127.0.0.1 > NUL 2>&1
echo.
ping -n 5 127.0.0.1 > NUL 2>&1
start explorer.exe
exit

Ignoring all the dumb / irritating things about this, I want to find out more about this part:
" > NUL 2>&1"
I know ">NUL" suppresses output from the screen without sending it to a file. What's going on with the part I underlined? The "&1" seems similar to "%0", "%1", "%2", etc (used for accepting input parameters).

...and here's what I find irritating:

• It uses the PING command only to show a message with mandatory delays. It does it before killing explorer.exe and before it launches explorer.exe (why add delays for no damn reason?!)
• There are two 5-ping delays added before starting explorer.exe (if you think the delay is needed, use a single 10-ping delay)
• "color 0B" is completely unnecessary.

[edit]
I guess the ampersand combines two commands on a single line. I still don't know what's going on with "2>&1"

 

[Tweak155]

The 2>&1 redirects all streams to the same output. This basically also means "any errors also go to echo / fstream (whichever you're specifying)".

I'm not using technical terms and probably am not describing it correctly - but basically any errors will also not be printed.

EDIT:

If I had to guess, that entire ping line is a lazy way to count to 5.

EDIT EDIT:

And to see more clearly what the 2>&1 does, intentionally write a command line that doesn't work into a file. Here is your exercise:

Write the following commands:

heythiswontwork > c:\test.txt

You'll see that the command line prompt informs you that it isn't a recognized command, and the text file is empty. Now try:

heythiswontwork > C:\test.txt 2>&1

You won't see a thing. It is now stored in the file (the error message received from the first test).

 

[Binky]

The ping is a pause. There is a period shown to the user between the two 5 second pauses. Other than that period, a 10 second pause would do the same thing.

 

[Ken g6]

There is a period shown to the user between the two 5 second pauses.

Actually, "echo." prints a blank line. It's a special case.

I didn't know 2>&1 worked in Windows. I've known about it for years in Linux, though.

I didn't see the other '&' usage in this batch file, but you mentioned it. A single & between commands ensures that both commands run, always. A double, &&, runs the second command only if the first worked without returning an error code. E.g.:

copy file1 file2 && del file1