I've got a new office and I must clean off my inherited whiteboard. The previous owner left various diagrams, code snippets, etc. on for such a time that they can no longer be erased
by conventional means: the whiteboard eraser is useless! I couldn't find any whiteboard cleaner either, but Ali told me the following secret. You can write over the dried on text with a normal dry
erase marker. When you erase the new markings the old are erased as well. It sounds too fantastic, but believe me, its true! I don't know the brand or material of the whiteboard but the whiteboard
markers are 'Expo, Bold Color Dry Erase'.
which command is a rather literal port and requires you to enter the entire name of the command for which you're looking. That is 'which which' won't find itself but
'which which.exe' will. This makes this almost useless for me so I thought to write my own as a batch file. I had learned about a few goodies available in cmd.exe that I thought would
make this an easy task. It turned out to be more difficult than I thought.for /F "usebackq tokens=*" %%a in ( `"echo %PATH:;=& echo %"` ) do (
for /F "usebackq tokens=*" %%b in ( `"echo %PATHEXT:;=& echo %"` ) do (
if exist "%%a"\%1%%b (
for %%c in ( "%%a"\%1%%b ) do (
echo %%~fc
)
)
)
)PATH and PATHEXT hold the list of paths to search through to find commands, and the extensions of files that should be run as
commands respectively. The 'for /F "usebackq tokens=*" %%a in (...) do (...)' runs the 'do' portion with %%a sequentially taking on the value of every line in
the 'in' portion. That's nice, but PATH and PATHEXT don't have their elements on different lines and I don't know of a way to escape a newline character to
appear in a batch file. In order to get the PATH and PATHEXT's elements onto different lines I used the %ENV:a=b% syntax which replaces occurrences of a with b
in the value of ENV. I replaced the ';' delimiter with the text '& echo ' which means %PATHEXT:;=& echo% evaluates to something like "echo .COM& echo
.EXE& echo .BAT& ...". I have to put the whole expression in double quotes in order to escape the '&' for appearing in the batch file. The usebackq and the backwards quotes means
that the backquoted string should be replaced with the output of the execution of its content. So in that fashion I'm able to get each element of the env. variable onto new lines. The rest is pretty
straight forward.C:\Users\davris>which.cmd *hi*
C:\Windows\System32\GRAPHICS.COM
C:\Windows\System32\SearchIndexer.exe
D:\bin\which.exe
D:\bin\which.cmd
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