Batch Maven build breaking cmd.exe?

Question

I had a Windows .bat file with a script for compilation of a project I'm working on. The last command is a maven build. Since it takes a while to finish, I wanted to be notified when it does.

I figured that the easiest way would be the equivalent to echo -e '\a' . So I looked around a bit and added echo <BELL>(<BELL> being a byte with the code 0x07) at the end of my script. I added echo in front of all commands for a quick test and it worked like a charm.

Removed the echos and ran the script. A few minutes later I notice it's finished. I didn't hear the bell, but assumed I just wasn't paying attention. Retested with echoes and it bell-ed just fine. However this has happened several times and I now know for a fact I'm not just missing it, it isn't there.

I've tried making a simple C program just running printf("\a") to the same results. I've then just tried an echo please work, this text didn't show up either. I've figured out that the difference is in the maven command being or not being echoed out. To sum up:

• Windows 10, Maven for Windows as last effective command in .bat batch script
• If mvn command is prepended with echo everythng works as it should
• If mvn command is ran subsequent commands in the .bat do not run
• Once the script finishes there appears to be nothing wrong with the cmd.exe instance

I have Cygwin (needed for the build) so if it's usefull for debugging that's not a problem.

EDIT: So it appears Maven is a batch file itself. Interrestingly, where mvn lists first bhahlabh\mnv (a bash script) and then blahblah\mvn.com

Answer 1

In Maven for Windows, the command 'mvn' refers to a batch script file called either mvn.bat or mvn.cmd (depending on the Maven version). Look in Maven's bin folder. In simple terms, a .bat file is a .cmd file, and vice versa. They are cmd.exe batch language scripts.

From the Maven web site:

You run Maven by invoking a command-line tool: mvn.cmd from the bin directory of the Maven. To do this conveniently, ${maven.home}\bin must be in your PATH, just like the Java SDK commands. You can add directories to your PATH in the control panel; the details vary by Windows version.

Maven on Windows

Under cmd.exe, if you run a second batch (.bat or .cmd) file from a first one, by using just its name, command transfers to the second one, and never returns.

Control comes back if you invoke the second script using the CALL command.

Example to show what I mean:

Here is a.bat (or a.cmd if you like)

@echo off
echo I am a.bat
b.bat
echo back again

Here is b.bat (or b.cmd if you like)

@echo off
echo I am b.bat

if you run a.bat, and b.bat is either in the same folder, or on your PATH, you will see this

I am a.bat
I am b.bat

You will not see back again, unless, in a.bat, you changed b.bat to call b.bat

Try putting CALL before 'mvn' in your batch.