[windows] What does "@" mean in Windows batch scripts

I saw @ is used in such contexts:

@echo off

@echo start eclipse.exe

What does @ mean here?

By default, a batch file will display its command as it runs. The purpose of this first command which @echo off is to turn off this display. The command "echo off" turns off the display for the whole script, except for the "echo off" command itself. The "at" sign "@" in front makes the command apply to itself as well.

It inherits the meaning from DOS. @:

In DOS version 3.3 and later, hides the echo of a batch command. Any output generated by the command is echoed.

Without it, you could turn off command echoing using the echo off command, but that command would be echoed first.

The @ disables echo for that one command. Without it, the echo start eclipse.exe line would print both the intended start eclipse.exe and the echo start eclipse.exe line.

The echo off turns off the by-default command echoing.

So @echo off silently turns off command echoing, and only output the batch author intended to be written is actually written.

Another useful time to include @ is when you use FOR in the command line. For example:

FOR %F IN (*.*) DO ECHO %F

Previous line show for every file: the command prompt, the ECHO command, and the result of ECHO command. This way:

FOR %F IN (*.*) DO @ECHO %F

Just the result of ECHO command is shown.

It means "don't echo the command to standard output".

Rather strangely,

echo off

will send echo off to the output! So,

@echo off

sets this automatic echo behaviour off - and stops it for all future commands, too.

Source: http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/batch.mspx?mfr=true

In batch file:

1 @echo off(solo)=>output nothing

2 echo off(solo)=> the “echo off” shows in the command line

3 echo off(then echo something) =>

4 @echo off(then echo something)=>

See, echo off(solo), means no output in the command line, but itself shows; @echo off(solo), means no output in the command line, neither itself;

you can include @ in a 'scriptBlock' like this:

@(
  echo don't echoed
  hostname
)
echo echoed

and especially do not do that :)

for %%a in ("@") do %%~aecho %%~a