Determine if command is recognized in a batch file

Question

I'm writing a bat script in which I invoke a program (such as javac). For simplicity, I want to check if the command exists before I run it. i.e. If the command exists in PATH.

For example,

if (my_command.exe is a recognized command) then (
  my_command.exe my_args
) else (
  REM Output was probably "'my_command.exe' is not recognized as an internal or external command, operable program or batch file."
  REM Do not run my_command.exe
)

What's the best way to do this in Windows?

Answer 1

If requiring the installation of extra tools is ok, there's a where command in the resource kits; see Windows equivalent of whereis?.

Otherwise, for versions of Windows that are not too ancient, it's doable in pure cmd, as mentioned in Dos executable lookup except PATH.

Answer 2

I know this not quite what you're looking for, but with a slight change in logic it should accomplish what you need.

Every command that is run has a return code (aka errorlevel), if the return code is 0 (zero), the command has run successfully, if the return code is greater than 0, something has gone wrong.

See here for more details.

Something like -

my_command
if (%ERRORLEVEL% > 0) then (
  REM Output was probably "'my_command.exe' is not recognized as an internal or external command, operable program or batch file.  OR SOMETHING WENT WRONG WITH IT."
  REM Do not run my_command.exe
)

Answer 3

The easiest way is to simply run the command, but that has other problems, of course, since maybe you don't want to have a random process started.

for %%x in (my_command.exe) do if not [%%~$PATH:x]==[] set MyCommandFound=1

is an alternative which searchs for the program in the paths listed by the %PATH% environment variable. It's essentially a pure batch version of which(1). It can be made better but essentially this is it.

Answer 4

While all those way might work, why not the built in way?

If exists my_command do echo "my_command exists"

Run "if /?" on the command line for details

Answer 5

For my situation. The absolute simplest way is using the || or && operator.

my_command.exe -version 2>NUL && echo "my_command exists"

or

my_command.exe -version 2>NUL || echo "my_command doesn't exist"