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This guide is aimed at Raspbian Linux (Stretch) on Raspberry PI, but should work on any Linux/UNIX like system DosBox supports.
To compile DosBox, you will need SDL 1.2 and SDL-net in addition to the usual development toolchain. You will also need Subversion to get dosbox and patch to patch it.
sudo apt-get install build-essential libsdl1.2-dev libsdl-net1.2-dev subversion automake
The most recent DosBox release has some issues with DOS doors, and the most recent Subversion code also has issues, so you will need a specific revision from the subversion repository. In my tests I have found r3933 to work well. Other revisions may work, but have not been tested.
svn checkout -r3933 svn://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk dosbox-code-0
Now we have the DosBox code, you will probably want to patch it to fix a specific bug that happens with some doors which will appear as though when you press enter, it receives the enter command twice.
wget https://gist.githubusercontent.com/apamment/bb438d9be6dc8e67c36239fd64047ece/raw/3e942c68d7a970f3404bffc2408165d810c4bef7/dosbox-nullmodem.diff cd dosbox-code-0 patch -p1 < ../dosbox-nullmodem.diff
Compiling DosBox takes a long time on the Raspberry PI and will appear to have frozen a few times - particularly when compiling the render-scalers file - don't worry, just leave it it will eventually move on.
./autogen.sh ./configure make sudo make install
These commands will compile and install DosBox into /usr/local/bin.
Next you will need to create a config file which enables the serial port for socket inheritance, and also mounts drives so that DosBox can access both your doors and your BBS drop files.
An example for my WWIV setup is here: dosbox.conf
In this example, drive C: is the location where my doors are stored and drive D: is the location of WWIV's temporary node files (drop files).
The shell script you need will vary from system to system, but basically, you want to:
* ensure no one else is using the door before you start it * make DosBox not use an X11 window, * ensure that the dropfiles have DOS line endings * launch DosBox with the command to start the batch file in the next section.
Some bulletin board systems have mechanisms to make sure only one person is using a door at a time, others do not. If your BBS system supports such a mechanism, you do not need to do it in the shell script.
Also some BBSes write dropfiles with DOS line endings instead of UNIX line endings, so you may not need to do that in the script.
Here is an example script I use for Freshwater Fishing on WWIV:
#!/bin/bash export SDL_VIDEODRIVER="dummy" NODE=$1 SOCKET=$2 /usr/bin/unix2dos /home/wwiv/temp/${NODE}/door.sys /usr/local/bin/dosbox -socket $SOCKET -c "C:\ffs.bat ${NODE}" -conf /home/wwiv/doors/dos/dosbox.conf
Notice my setup does not need to check if the door is in use, but it does need to convert the drop file to use DOS line endings.
An example where you can check if the door is in use would be:
#!/bin/bash export SDL_VIDEODRIVER="dummy" NODE=$1 SOCKET=$2
if [ ! -e /home/wwiv/doors/dos/ffs.inuse ]; then touch /home/wwiv/doors/dos/ffs.inuse /usr/bin/unix2dos /home/wwiv/temp/${NODE}/door.sys /usr/local/bin/dosbox -socket $SOCKET -c "C:\ffs.bat ${NODE}" -conf /home/wwiv/doors/dos/dosbox.conf rm /home/wwiv/doors/dos/ffs.inuse fi
This will just dump the user back to the BBS if the door is in use. You could get fancy and use the 'inuse' door I created which will display an in-use message and then quit (INUSE Door), but that is outside the scope of this document.