Ps is implemented by parsing /proc, so the results you get are the same. Having said that, /proc/xxx/status does contain a flag that tells you whether a proces

Ps is implemented by parsing /proc, so the results you get are the same. Having said that, /proc/xxx/status does contain a flag that tells you whether a process is a zombie or not. So on Linux, Phusion Passenger parses that file as an extra check. But not all software does this.