Redirecting output to null in PowerShell but ensuring the variable remains set

Question

I have some code    foo   someFunction   This outputs a warning message which I want to redirect to  null    foo   someFunction  gt   null   The problem is that when I do this  while successfully supressing the warning message  it also has the negative side-effect of NOT populating  foo with the result of the function   How do I redirect the warning to  null  but still keep  foo populated   Also  how do you redirect both standard output and standard error to null   In Linux  it s 2 gt  amp 1

User · Answer

If it s errors you want to hide you can do it like this   ErrorActionPreference    SilentlyContinue    This will hide errors  someObject SomeFunction     ErrorActionPreference    Continue    Turning errors back on

User · Answer

Warning messages should be written using the Write-Warning cmdlet  which allows the warning messages to be suppressed with the -WarningAction parameter or the  WarningPreference automatic variable  A function needs to use CmdletBinding to implement this feature   function WarningTest        CmdletBinding        param  n       Write-Warning  This is a warning message for   n        Parameter n    n      a   WarningTest  test one  -WarningAction SilentlyContinue    To turn off warnings for multiple commads    use the WarningPreference variable  WarningPreference    SilentlyContinue   b   WarningTest  test two   c   WarningTest  test three    Turn messages back on   WarningPreference    Continue   c   WarningTest  test four    To make it shorter at the command prompt  you can use -wa 0   PS gt  WarningTest  parameter alias test  -wa 0   Write-Error  Write-Verbose and Write-Debug offer similar functionality for their corresponding types of messages

User · Answer

I d prefer this way to redirect standard output  native PowerShell        foo   someFunction    out-null   But this works too     foo   someFunction   gt   null   To redirect just standard error after defining  foo with result of  someFunction   do    foo   someFunction  2 gt   null   This is effectively the same as mentioned above   Or to redirect any standard error messages from  someFunction  and then defining  foo with the result    foo    someFunction 2 gt   null    To redirect both you have a few options   2 gt  amp 1 gt  null 2 gt  amp 1   out-null

User · Answer

This should work     foo   someFunction 2 gt  null

User · Answer

using a function   function run command   command        invoke-expression   command   gt  null      return       if    run command  dir   txt          if    run command  dir   doc                  run command  dir                or if you like one-liners   function run command   command    invoke-expression   command    out-null  return       if    run command  dir   txt      if    run command  dir   doc      run command  dir

[powershell] Redirecting output to $null in PowerShell, but ensuring the variable remains set

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