How can I increase the maximum number of characters read by Read-Host? - powershell

Question

I need to get a very long string input (around 9,000 characters), but Read-Host will truncate after around 8,000 characters. How can I extend this limit?

Answer 1

The following are possible workarounds.
Workaround 1 has the advantage that it will work with PowerShell background jobs that require keyboard input. Note that if you are trying to paste clipboard content containing new lines, Read-HostLine will only read the first line, but Read-Host has this same behavior.
Workaround 1:
<#
.SYNOPSIS
Read a line of input from the host.
.DESCRIPTION
Read a line of input from the host.
.EXAMPLE
$s = Read-HostLine -prompt "Enter something"
.NOTES
Read-Host has a limitation of 1022 characters.
This approach is safe to use with background jobs that require input.
If pasting content with embedded newlines, only the first line will be read.
A downside to the ReadKey approach is that it is not possible to easily edit the input string before pressing Enter as with Read-Host.
#>
function Read-HostLine ($prompt = $null) {
if ($prompt) {
"${prompt}: " | Write-Host
}
$str = ""
while ($true) {
$key = $host.UI.RawUI.ReadKey("NoEcho, IncludeKeyDown");
# Paste the clipboard on CTRL-V
if (($key.VirtualKeyCode -eq 0x56) -and # 0x56 is V
(([int]$key.ControlKeyState -band [System.Management.Automation.Host.ControlKeyStates]::LeftCtrlPressed) -or
([int]$key.ControlKeyState -band [System.Management.Automation.Host.ControlKeyStates]::RightCtrlPressed))) {
$clipboard = Get-Clipboard
$str += $clipboard
Write-Host $clipboard -NoNewline
continue
}
elseif ($key.VirtualKeyCode -eq 0x08) { # 0x08 is Backspace
if ($str.Length -gt 0) {
$str = $str.Substring(0, $str.Length - 1)
Write-Host "`b `b" -NoNewline
}
}
elseif ($key.VirtualKeyCode -eq 13) { # 13 is Enter
Write-Host
break
}
elseif ($key.Character -ne 0) {
$str += $key.Character
Write-Host $key.Character -NoNewline
}
}
return $str
}
Workaround 2:
$maxLength = 65536
[System.Console]::SetIn([System.IO.StreamReader]::new([System.Console]::OpenStandardInput($maxLength), [System.Console]::InputEncoding, $false, $maxLength))
$s = [System.Console]::ReadLine()
Workaround 3:
function Read-Line($maxLength = 65536) {
$str = ""
$inputStream = [System.Console]::OpenStandardInput($maxLength);
$bytes = [byte[]]::new($maxLength);
while ($true) {
$len = $inputStream.Read($bytes, 0, $maxLength);
$str += [string]::new($bytes, 0, $len)
if ($str.EndsWith("`r`n")) {
$str = $str.Substring(0, $str.Length - 2)
return $str
}
}
}
$s = Read-Line
More discussion here:
Console.ReadLine() max length?
Why does Console.Readline() have a limit on the length of text it allows?
https://github.com/PowerShell/PowerShell/issues/16555