Friday, February 24, 2012

Ever wanted to use the Unix "which" command on Windows?

The which Unix command takes a program name as an argument, and gives you the first matching directory on your path which contains that program. This is useful if, for example, you're trying to uninstall or upgrade software and are trying to figure out why you can still call the program after you thought it'd been deleted.

Unfortunately, there doesn't seem to be any kind of related command for DOS. Happily, a user named Mechanix2Go posted a hackish version which you can save as a batch file. I've made a couple of minor tweaks, to suppress file not found errors and fix the frankly idiotic treatment by DOS of the PATH variable as a set of tokens delimited by spaces. Some horrible hackery was taken from here to partially work around the problem. It will still fall over on weird paths with a ';' in them, and it'll echo double quotes.
Trying to express yourself in DOS batch language is like trying to compose a symphony using only two piano strings.

@echo off & setLocal EnableDelayedExpansion

if %1'==' goto :eof

for %%a in ("%path:;=";"%") do (
  dir /b %%a 2>&1 | findstr /i /b /c:"%1.exe" /c:"%1.bat" /c:"%1.com" > nul
  if not errorlevel 1 echo %1 is in %%~a && goto :eof
)

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