What does 2>&1 Mean in PowerShell

Question

I have the following script:

if( $timeout -ne $null )
{
    & $var$timeout 2>&1 > $logDir\$logName
}
else
{
    & $var2>&1 >  $logDir\$logName
}

I'm curious about what 2>&1 is; or, what it represents. I don't know what it's called, otherwise, I'd look it up.

possible duplicate of [In the shell, what is " 2>&1 "?](http://stackoverflow.com/questions/818255/in-the-shell-what-is-21) — x0n, Jul 29 '13 at 18:20
`2>&1` looks like IO-redirection to me... but I'm not all that familiar with powershell. — Alexej Magura, Jul 29 '13 at 18:20
@x0n does answer that apply to Windows? It looks like Unix to me; is there any difference? — BlackHatSamurai, Jul 29 '13 at 18:22
@Blaine Yes, that applies to Windows, which took the syntax directly from Unix shells. — x0n, Jul 29 '13 at 19:45

score 42 · Accepted Answer · answered Jul 29 '13 at 18:53

42

It redirects standard error (the 2) to the same place as standard output (the 1)

answered Jul 29 '13 at 18:53

Sean

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score 33 · Answer 2 · answered Jul 29 '13 at 18:57

The docs are your friends. From PS> man about_Redirection

The Windows PowerShell redirection operators are as follows.

Operator  Description                Example
--------  ----------------------     ------------------------------
<snip>

2>&1      Sends errors (2) and       Get-Process none, Powershell 2>&1
          success output (1)
          to the success
          output stream.

<snip>

The syntax of the redirection operators is as follows:

   <input> <operator> [<path>\]<file>

If the specified file already exists, the redirection operators that do not
append data (> and n>) overwrite the current contents of the file without
warning. However, if the file is a read-only, hidden, or system file, the
redirection fails. The append redirection operators (>> and n>>) do not
write to a read-only file, but they append content to a system or hidden
file.

Thank you for the answer, but as I said in my post, how can I search for something if I don't know what it is. If I knew it was redirection, I'd be able to use your answer, and wouldn't have needed to post. — BlackHatSamurai, Jul 29 '13 at 20:13
You can search the help system with wildcards. `Get-Help '*&1*'` points to the above topic. — latkin, Jul 29 '13 at 20:32

What does 2>&1 Mean in PowerShell

2 Answers2

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