Making PowerShell history persist between sessions.

Persist History.ps1

# Usage: run this file, it will install itself
#        to $profile and be run from there

# Make sure $profile exists.
if (! (Test-Path $profile) ) {
  New-Item -Path $profile -ItemType File -Force
}

# Find ourselves and where we should be.
$me = $PSCommandPath   # $MyInvocation.MyCommand.Definition
$destiny = $(Resolve-Path '~\Documents\WindowsPowerShell').ToString() + "\persist_history.ps1"

# Install script if needed.
if (! ($me -eq $destiny) ) {

  # Copy ourselves.
  Copy-Item $me $destiny

  # Append calling this script to $profile.
  Add-Content $profile "`nInvoke-Expression -Command $destiny"

}

# Save history on exit.
Register-EngineEvent PowerShell.Exiting -Action {
  Get-History -Count 4KB | Export-CSV ~\Documents\WindowsPowerShell\powershell_history.csv
} > $null   # silence output

# Load previous history if it exists.
if (Test-Path ~\Documents\WindowsPowerShell\powershell_history.csv) {
  Import-CSV ~\Documents\WindowsPowerShell\powershell_history.csv | Add-History
}