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# Debugging the Main Process
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The browser window DevTools can only debug the renderer process scripts (i.e.
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the web pages). In order to provide a way to debug the scripts from the main
process, Electron has provided the `--debug` and `--debug-brk` switches.
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## Command Line Switches
Use the following command line switches to debug Electron's main process:
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### `--debug=[port]`
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When this switch is used Electron will listen for V8 debugger protocol
messages on `port` . The default `port` is `5858` .
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### `--debug-brk=[port]`
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Like `--debug` but pauses the script on the first line.
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## Use node-inspector for Debugging
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**Note:** Electron doesn't currently work very well
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with node-inspector, and the main process will crash if you inspect the
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`process` object under node-inspector's console.
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### 1. Make sure you have [node-gyp required tools][node-gyp-required-tools] installed
### 2. Install [node-inspector][node-inspector]
```bash
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$ npm install node-inspector
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```
### 3. Install a patched version of `node-pre-gyp`
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```bash
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$ npm install git+https://git@github.com/enlight/node-pre-gyp.git#detect-electron-runtime-in-find
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```
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### 4. Recompile the `node-inspector` `v8` modules for electron (change the target to your electron version number)
```bash
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$ node_modules/.bin/node-pre-gyp --target=0.36.11 --runtime=electron --fallback-to-build --directory node_modules/v8-debug/ --dist-url=https://atom.io/download/atom-shell reinstall
$ node_modules/.bin/node-pre-gyp --target=0.36.11 --runtime=electron --fallback-to-build --directory node_modules/v8-profiler/ --dist-url=https://atom.io/download/atom-shell reinstall
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```
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See also [How to install native modules][how-to-install-native-modules].
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### 5. Enable debug mode for Electron
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You can either start Electron with a debug flag like:
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```bash
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$ electron --debug=5858 your/app
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```
or, to pause your script on the first line:
```bash
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$ electron --debug-brk=5858 your/app
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```
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### 6. Start the [node-inspector][node-inspector] server using electron
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```bash
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$ ELECTRON_RUN_AS_NODE=true path/to/electron.exe node_modules/node-inspector/bin/inspector.js
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```
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### 7. Load the debugger UI
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Open http://127.0.0.1:8080/debug?ws=127.0.0.1:8080& port=5858 in the Chrome browser. You may have to click pause if starting with debug-brk to see the entry line.
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[node-inspector]: https://github.com/node-inspector/node-inspector
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[node-gyp-required-tools]: https://github.com/nodejs/node-gyp#installation
[how-to-install-native-modules]: using-native-node-modules.md#how-to-install-native-modules