In order:
pid
: The is the process ID (PID) of the process you call theProcess.pid
method in.ppid
: The PID of the parent process (the process that spawned the current one). For example, if you runruby test.rb
in a bash shell, PPID in that process would be the PID of Bash.uid
: The UNIX ID of the user the process is running under.euid
: The effective user ID that the process is running under. The EUID determines what a program is allowed to do, based on what the user with this UID is allowed to do. Typically the same asuid
, but can be different with commands likesudo
.gid
: The UNIX group ID the program is running under.egid
: Likeeuid
, but for groups.