Linux: How to compile C++ scripts from terminal

Hi all,

Just wanted to share a discovery I had trying to set up my favourite “IDE”: vim + bash:
It’s possible to invoke C++ script compilation from terminal and have it working with the editor’s hot reload function.
I made this script based on the information in the output log.

Add this function to your ~/.bashrc:

function unrealbuild {
    RANDNUM=$(( ( RANDOM % 1000 ) + 1000 ));
    PROJ_NAME=$(basename ${1%.uproject});

    echo $RANDNUM

    ${UNR_PATH}/Engine/Build/BatchFiles/Linux/ ${UNR_PATH}/Engine/Binaries/DotNET/UnrealBuildTool.exe $PROJ_NAME -ModuleWithSuffix $PROJ_NAME $RANDNUM Linux Development -editorrecompile -canskiplink "${CURR_DIR}/${PROJ_NAME}.uproject" -progress

(Of course, replace the “/opt/UnrealEngine” bit with the path to your UnrealEngine folder.)

And then use it like this:

cd /path/to/ProjectName
unrealbuild ./ProjectName.uproject

The part I’m not so certain of is the purpose of the RANDNUM variable. I found that it only works if I create a new random number every time.
I don’t know if the numbers the built-in compiler tool uses are being tracked in the editor to be deleted later on, and if this script will generate a bunch of garbage binaries that way.

In any case, the binaries are going to the /path/to/ProjectName/Binaries/Linux folder, you can keep an eye on them there.

If anyone has anything to add, perhaps making it more flexible, it’d be highly appreciated.

Thank you oh so very much.
I too have been fighting with the build process to get Hot Reload to work from the command line in Linux.

This is perfect and should be added to the official documentation.

Nice one !! This is a much saner way to compile :slight_smile: Thanks !

Hello, This isn’t working on my system.

cagdas@desktop:~/Documents/Unreal Projects/Time$ unrealbuild Time.uproject

Running Mono...

Fixing inconsistent case in filenames.
Setting up Mono
~/programs/UnrealEngine/Engine ~/Documents/Unreal Projects/Time
ERROR: '-ModuleWithSuffix <Name> <Suffix>' syntax is no longer supported on the command line. Use '-Module=<Name>,<Suffix>' instead.
       (see ../Programs/UnrealBuildTool/Log.txt for full exception trace)

I’ve tried changing it to this:

    ${UNR_PATH}/Engine/Build/BatchFiles/Linux/ ${UNR_PATH}/Engine/Binaries/DotNET/UnrealBuildTool.exe $PROJ_NAME -Module=$PROJ_NAME,$RANDNUM Linux Development -editorrecompile -canskiplink "${CURR_DIR}/${PROJ_NAME}.uproject" -progress

But this also doesn’t work and throws error like it doesn’t know what ‘module’ means.

ERROR: One or more of the modules specified using the '-module' argument could not be found.
       (see ../Programs/UnrealBuildTool/Log.txt for full exception trace)

Anyone has this issue or know the solution to this?

Not sure if it is okay to post in a dead thread like this, but I didn’t see anything about it in the forum rules. I will gladly make a new thread about compiling code on the Linux platform if asked by the moderators.

From my understanding reading through the code, you need to use the following command line argument.


That is, include the comma in the command line argument and it should work. I was reading through the code in an attempt to respond to OP’s question about the suffix number that is needed for a hot reload. Here’s what I found in the source.

// Patch action history for hot reload when running in assembler mode. In assembler mode, the suffix on the output file will be
// the same for every invocation on that makefile, but we need a new suffix each time.
// For all the hot-reloadable modules that may need a unique suffix appended, build a mapping from output item to all the output items in that module. We can't
// apply a suffix to one without applying a suffix to all of them.

It seems to me like the purpose of this is for appending a build number, but it is a little weird that it only accepts ints, so you can’t have a proper build number like 1.13.0 for example.