Dynamic Help Custom Pager Support

[JustinGrote]

Description of the new feature/enhancement

While a native pager is welcome especially for windows users, linux users may want to use the pager for dynamic help they are more comfortable with (less, etc.)

Proposed technical implementation details (optional)

There should be a psreadlineoption to specify an alternate pager and arguments. Dynamic help will simply call that pager and provide the help content to it via stdout

[lzybkr]

The semi-official PAGER environment variable should be honored if set, but maybe a PSReadLine specific option is necessary as well.

[ninmonkey]

The semi-official PAGER environment variable should be honored if set,

On Win10 the new help key is ignoring $Env:Pager

PS> $PSVersionTable | % PSVersion | % tostring
7.1.2                                         
                                              
PS> Get-Module PSReadLine                     
                                              
ModuleType Version    PreRelease Name         
---------- -------    ---------- ----         
Script     2.2.0      beta2      PSReadLine   
                                              
                                              
PS> $env:Pager                                
less                                          
  
# verify it exists                                            
PS> gcm less                                  
                                              
CommandType     Name                          
-----------     ----                          
Application     less.exe                      

[daxian-dbw]

/cc @adityapatwardhan for comments

[KyleKolander]

If I use the help function, it honors my system-defined PAGER (environment variable). Can we please get an option to support this behavior? The default behavior could stay as-is for backward compatibility, but those of us who have customized our environment could turn on this option and this would work as expected.

help Get-CommandDefinition

For reference, I have the following environment variables defined to support paging:

> $env:PAGER
less

> $env:LESS
--RAW-CONTROL-CHARS --LONG-PROMPT --use-color --chop-long-lines --file-size --status-column

> $env:LESSCHARSET
UTF-8

The native PowerShell Pager implementation is much too limited, IMO. For example, when the help content is somewhat lengthy, it takes a long time to scroll down line by line if I enter help via the PSReadLine F1 binding. If I enter via the help function, it's fully featured. I intentionally entered the request here as opposed to the PowerShell Pager repo, because I believe PSReadLine is too tightly coupled to that one implementation of a pager.

Thanks for adding the F1 help option - really good idea! But please allow us to be more productive/efficient by supporting the PAGER environment variable.