Determine the current text encoding of your Windows

$Enc = [System.Text.Encoding]::Default
Write-Host "Encoding name: " $Enc.EncodingName
Write-Host "=================================================="
Write-Host "Code page:     " $Enc.CodePage
Write-Host "Web name:      " $Enc.WebName
Write-Host "Header name:   " $Enc.HeaderName " (destined for e-mail applications)"
Write-Host "Body name:     " $Enc.BodyName " (destined for e-mail applications)"
Write-Host

Batch equivalent to: $(dirname ${0})/$(basename ${0} .<old_suffix>)<new_suffix>

Actually it is not PowerShell but useful in bat scripts starting PowerShell scripts.

%~dp0%~n0.ps1

If you want to use it in the previous post, you cannot put it in a variable first if the result contains space characters. For some obscure reason. Not connected with this fomula.

P:\My : The term 'P:\My' is not recognized as the name of a cmdlet,...

Error

Calling following gives the below error message.

powershell P:\My Roaming Documents\create_db_patch_deployment_package.ps1

P:\My : The term 'P:\My' is not recognized as the name of a cmdlet,...

Solution

Use call

powershell -File "P:\My Roaming Documents\create_db_patch_deployment_package.ps1"

module '%~dp0' could not be loaded

Error

Calling following gives the below error message. %~dp0 on the Windows command prompt is the equivalent of the bash dirname $0

powershell %~dp0\create_db_patch_deployment_package.ps1

%~dp0\create_db_patch_deployment_package.ps1 : The module '%~dp0' could not be loaded. For more information, run 'Import-Module %~dp0'.

Solution

Use call

powershell -File "%~dp0\create_db_patch_deployment_package.ps1"

Write files without byte order mark (BOM)

If you use Out-File with -Encoding utf8 you invariably get a file where the first three bytes mark the byte order. This can break the further processing of the file, e. g. SQL+ is incapable to cope with it... why does Oracle support UTF-8 anyway ;-).
To get arround this, you can use [System.IO.File]::WriteAllLines with the proper encoding, e.g.

$UTF8NoBomEncoding = New-Object System.Text.UTF8Encoding(
      $False,
      $True)
[System.IO.File]::WriteAllLines(
      $outputFilePath,
      $array,
      $UTF8NoBomEncoding)

Equivalent to grep being used in a pipe

Select-String (official documentation)

To search files recursively: Get-ChildItem -Path "path" | Select-String -Pattern "to look for" -CaseSensitive (official documentation of Get-ChildItem)

@ => Unrecognized token in source text.

Error

At P:\My Roaming Documents\west-3325\west_3325.ps1:12 char:48
+ $Result=sqlplus SDM_DATA/SDM_DATA_DEV@D52PMDWH @ west_3325.sql
+                                                ~
Unrecognized token in source text.
    + CategoryInfo          : ParserError: (:) [], ParseException
    + FullyQualifiedErrorId : UnrecognizedToken

Problem

@ is a special character in PowerShell:

 @(...)                 Force an expression to be evaluated as an array

Solution

Use a tic to escape it:

$Result=sqlplus SDM_DATA/SDM_DATA_DEV@D52PMDWH `@ west_3325.sql

Create user interface dynamically, where users can select from a choice

$patchNames = ("P1", "P2", "P3")  # You probably want to create that dynamically. This seems to be the whole point.
$patchIndex = -1
$patchOptions = @()
foreach ($patchName in $patchNames) {
      $patchIndex++
      $patchOptions += New-Object `
         System.Management.Automation.Host.ChoiceDescription `
         "${patchName}"
}
$options = [System.Management.Automation.Host.ChoiceDescription[]]$patchOptions
$patchIndex = $host.ui.PromptForChoice(
   "Patch-Auswahl",
   "Bitte den Patch anhand des Namens auswählen (z. B. Copy-Paste). " + `
   "Vorausgewählt ist der jüngste, der mit einfachem Enter-Drücken " + `
   "ausgewählt wird",
   $options,
   0
)
$patchName = $patchNames[${patchIndex}]

Zip files and directories

Add-Type -Assembly System.IO.Compression.FileSystem
$compressionLevel = [System.IO.Compression.CompressionLevel]::Optimal
$zipFilePath = `
   $ExecutionContext.SessionState.Path.GetUnresolvedProviderPathFromPSPath(
         "${scriptDirPath}\..\software-lieferung\${patchName}.zip"
   )
if (Test-Path -path "${zipFilePath}") {
      Write-Debug("Removing ${zipFilePath}")
      Remove-Item -path "${zipFilePath}" -force
}
[System.IO.Compression.ZipFile]::CreateFromDirectory(
      "${tmpPatchDirPath}",
      "${zipFilePath}",
      $compressionLevel,
      $False
)

Command output is an array of lines

If you need to have it as a single string, -join "`n" the output or pipe the output through Out-String.

Problem

You need to replace a string containing double $$ using regular expression by a string containing a double $, e. g. original string $$Reusable_only_switch= replacement string $$Reusable_only_switch=true.

Solution

Put the $$ in a group and make the group part of the replacement string, e. g. regular expression ^(\$\$Reusable_only_switch=)\s*$ replacement expression $1true.

Shortcoming

If the double $ needs to end up at a different position, for the time being I do not see other solution but to take several steps.

Create empty zip file

if (
       -not (
            Test-Path `
                -Path $pathAbsoluteArchiveFile `
                -PathType Leaf
       )
 ) {
       Set-Content -Path $pathAbsoluteArchiveFile (
             "PK" + [char]5 + [char]6 + ("$([char]0)" * 18))
 }