bash installer should install php-mbstring along with php-cli
Short version: the initial bash installer script should install php-mbstring along with php-cli.
Installing on a very minimal Debian 10 system, the initial bash installer script (get.ispconfig.org) installed php-cli but did not install the php-mbstring package; prior to fully running the php installer I wanted to see available options, so ran with --help, and it produced the error:
PHP Fatal error: Uncaught Error: Call to undefined function mb_strlen() in /tmp/ispconfig-ai/lib/class.ISPConfigLog.inc.php:74
Stack trace:
#0 /tmp/ispconfig-ai/lib/class.ISPConfig.inc.php(232): ISPConfigLog::print('\n\n{FW}*\nISPConf...')
#1 /tmp/ispconfig-ai/lib/class.ISPConfig.inc.php(260): ISPConfig::printHelp()
#2 /tmp/ispconfig-ai/ispconfig.ai.php(13): ISPConfig::run()
#3 {main}
thrown in /tmp/ispconfig-ai/lib/class.ISPConfigLog.inc.php on line 74
I don't know if there are any other packages required to run the php installer, that's all I've encountered, but if so, they should likely be installed as well.