Batch/Shell script to update to text file arguments

Question

I have a text file with the contents example.txt

My name is {param1}
I live in {param2}
These are all the parameters passed to batch scripts {params}

How should i write and Batch/shell script to pass arguments to example.txt file

Answer 1

Caveat: Use the following solutions only with input files that you trust, because it is possible to embed arbitrary commands inside the text (preventing that is possible, but requires more work):

In a PowerShell script, named, say Expand-Text.ps1:

# Define variables named for the placeholders in the input file,
# bound to the positional arguments passed.
$param1, $param2, $params = $args[0], $args[1], $args

# Read the whole text file as a single string.
$txt = Get-Content -Raw example.txt

# Replace '{...}' with '${...}' and then use
# PowerShell's regular string expansion (interpolation).
$ExecutionContext.InvokeCommand.ExpandString(($txt -replace '\{', '${'))

Calling .\Expand-Text.ps1 a b c then yields:

My name is a
I live in b
These are all the parameters passed to batch scripts a b c

---

In a batch file, named, say expandText.cmd, using PowerShell's CLI:

@echo off

:: # \-escape double quotes so they're correctly passed through to PowerShell
set params=%*
set params=%params:"=\"%

:: "# Call PowerShell to perform the expansion.
powershell.exe -executionpolicy bypass -noprofile -c ^
  "& { $txt = Get-Content -Raw example.txt; $param1, $param2, $params = $args[0], $args[1], $args; $ExecutionContext.InvokeCommand.ExpandString(($txt -replace '\{', '${')) }" ^
  %params%