| name | bat-powershell-caution |
| description | Fires when writing, fixing, or debugging batch scripts (.bat / .cmd) or PowerShell scripts (.ps1). |
Cautions for batch scripts / PowerShell
Known batch-script problems
When a complex batch script (logging, subroutines, error handling, etc.)
exits silently or behaves unexpectedly, suspect the following:
Parenthesis-parsing problem
A ) inside a message is mis-parsed as the terminator of an if/else block.
call nesting + exit /b problem
When call other.bat followed by exit /b happens inside call :label,
the execution context gets corrupted.
Delayed-expansion trap
Mixing !variable! and %variable% causes unexpected expansion.
Known PowerShell problems
Adding comments inside a .ps1 param() block (no non-ASCII)
Windows PowerShell 5.x reads a BOM-less .ps1 as CP932 (ANSI). Because of this,
a non-ASCII (e.g. Japanese) comment inside the param() block causes the
multibyte sequence to be misread and breaks param parsing
(NamedParameterNotFound, parameter not found, etc.).
A non-ASCII comment at the top of the module is harmless, but inside the
param structure it is dangerous.
Mitigation (either one):
- Write any comment added inside
param() in ASCII
- Or save the script with a UTF-8 BOM so PowerShell recognizes it as UTF-8
Recommended response
- Switching to PowerShell is recommended. The problems above do not occur in PowerShell.
- If double-click launch is required, use a
.ps1 + .cmd wrapper.
- If keeping batch, minimize subroutines and parenthesis blocks.
