Possible to have conditional pipes in PowerShell?

Question

Say I only want to pipe my output to another function depending on the value of a variable, is there some way to do this in powershell?

Example :

 if ($variable -eq "value"){$output | AnotherFunction}
  else {$output}

@mjolinor's example is how I am doing it now, just curious if there is a better way to do it.

-1 - give some explanation of what you want to do. @mjolinor 's anwser is appropriate, but I would have thought it to be trivial. — manojlds, May 19 '11 at 17:12
Might be trivial. I haven't used PowerShell before so I'm trying to figure out if there is a more elegant way to do it. Sorry if I offended you. — Abe Miessler, May 19 '11 at 17:16
I don't know if you'd consider it "more elegant" or not, but you can implement that logic as a filter. I updated my answer with an example. — mjolinor, May 19 '11 at 18:23
See http://stackoverflow.com/a/20123883/223837 for another answer. — MarnixKlooster ReinstateMonica, Nov 21 '13 at 16:12

mjolinor · Accepted Answer · 2011-05-19T18:22:21.150

6

You can use an If clause:

 if ($variable -eq "value"){$output | AnotherFunction}
  else {$output}

Example implemented as a fiter:

 filter myfilter{
   if ($variable -eq "value"){$_ | AnotherFunction}
   else {$_}
 }

Then:

 $variable = <some value>
 get-something | myfilter

edited May 19 '11 at 18:22

answered May 19 '11 at 16:57

mjolinor

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daalbert · Answer 2 · 2011-05-19T17:31:34.800

3

You may get the results you are looking for by piping to the Where-Object.

Example:

My-Command | Where-Object {$variable -eq "value"} | AnotherFunction

edited May 19 '11 at 17:31

answered May 19 '11 at 16:27

daalbert

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I don't see how that would allow conditional piping. Do you have an example? – Abe Miessler May 19 '11 at 16:50
Do you want to output to different functions depending on the output, or do you want to output to 1 function, but only if the output is what you want it to be? – daalbert May 19 '11 at 17:07
Pretty much the way that @mjolinor has it setup. I was wondering if there was a better way, but it sounds like there might not be. – Abe Miessler May 19 '11 at 17:24
I updated my answer with an example. AnotherFunction will get passed only what passes the condition of Where-Object. – daalbert May 19 '11 at 17:34
1

But when $variable -eq "value" is $false, nothing is returned. That's why this approach doesn't work. – stej May 19 '11 at 18:17
@stej that is correct, but many functions/cmdlets will gracefully exit when passed nothing. Try running `Get-Process | Where-Object {$_.handles -lt 100} | Format-List`, then change the 100 to 0 and run it again. – daalbert May 19 '11 at 18:40

score 0 · Answer 3 · answered May 19 '11 at 19:15

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If the other function is yours, you can send $variable as a parameter and let your function pass the object through unmodified when param is true. Essentially, you use AnotherFunction() as Mjolinor's filter.

answered May 19 '11 at 19:15

codepoke

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score 0 · Answer 4 · edited May 23 '17 at 11:59

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In this question I've asked how to use if statements inside pipeline. It demonstrates how to pipe data to other functions based on conditions.

edited May 23 '17 at 11:59

Community

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answered May 19 '11 at 20:14

Emiliano Poggi

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Possible to have conditional pipes in PowerShell?

4 Answers4