Classes/Console/Install/Action/PrepareInstallAction.php
private function ensureInstallationIsPossible(array $options)
    {
        $integrityCheck = $options['integrityCheck'] ?? false;
        if (!$integrityCheck) {
            return;
        }

        $isInteractive = $options['interactive'] ?? $this->output->getSymfonyConsoleInput()->isInteractive();
        $forceInstall = $options['forceInstall'] ?? false;

        $localConfFile = PATH_typo3conf . 'LocalConfiguration.php';
        $packageStatesFile = PATH_typo3conf . 'PackageStates.php';
        if (!$forceInstall && file_exists($localConfFile)) {
            $this->output->outputLine();
            $this->output->outputLine('<error>TYPO3 seems to be already set up!</error>');
            $proceed = $isInteractive;
            if ($isInteractive) {
                $this->output->outputLine();
                $this->output->outputLine('<info>If you continue, your <code>typo3conf/LocalConfiguration.php</code></info>');
                $this->output->outputLine('<info>and <code>typo3conf/PackageStates.php</code> files will be deleted!</info>');
                $this->output->outputLine();
                $proceed = $this->output->askConfirmation('<info>Do you really want to proceed?</info> (<comment>no</comment>) ', false);
            }
            if (!$proceed) {
                $this->output->outputLine('<error>Installation aborted!</error>');
                throw new InstallationFailedException('Installation aborted by user', 1529926774);
            }
        }
        @unlink($localConfFile);
        @unlink($packageStatesFile);
        clearstatcache();
        if (file_exists($localConfFile)) {
            $this->output->outputLine();
            $this->output->outputLine('<error>Unable to delete configuration file!</error>');
            $this->output->outputLine('<error>Installation aborted!</error>');
            throw new InstallationFailedException('Installation aborted because of insufficient premissions', 1529926810);
        }
    }
private function ensureInstallationIsPossible(array $options)
    {
        $integrityCheck = $options['integrityCheck'] ?? false;
        if (!$integrityCheck) {
            return;
        }

        $isInteractive = $options['interactive'] ?? $this->output->getSymfonyConsoleInput()->isInteractive();
        $forceInstall = $options['forceInstall'] ?? false;

        $localConfFile = PATH_typo3conf . 'LocalConfiguration.php';
        $packageStatesFile = PATH_typo3conf . 'PackageStates.php';
        if (!$forceInstall && file_exists($localConfFile)) {
            $this->output->outputLine();
            $this->output->outputLine('<error>TYPO3 seems to be already set up!</error>');
            $proceed = $isInteractive;
            if ($isInteractive) {
                $this->output->outputLine();
                $this->output->outputLine('<info>If you continue, your <code>typo3conf/LocalConfiguration.php</code></info>');
                $this->output->outputLine('<info>and <code>typo3conf/PackageStates.php</code> files will be deleted!</info>');
                $this->output->outputLine();
                $proceed = $this->output->askConfirmation('<info>Do you really want to proceed?</info> (<comment>no</comment>) ', false);
            }
            if (!$proceed) {
                $this->output->outputLine('<error>Installation aborted!</error>');
                throw new InstallationFailedException('Installation aborted by user', 1529926774);
            }
        }
        @unlink($localConfFile);
        @unlink($packageStatesFile);
        clearstatcache();
        if (file_exists($localConfFile)) {
            $this->output->outputLine();
            $this->output->outputLine('<error>Unable to delete configuration file!</error>');
            $this->output->outputLine('<error>Installation aborted!</error>');
            throw new InstallationFailedException('Installation aborted because of insufficient premissions', 1529926810);
        }
    }
Handles the case when LocalConfiguration.php file already exists

@param array $options
@throws InstallationFailedException