kevin@msa3b.UUCP (Kevin P. Kleinfelter) (10/18/89)
What is a process group? I know the following things: You can make a process the process group leader via setpgrp(); (with some versions of UNIX) You can send a signal to all members of a process group I have inherited some code which does pid = setpgrp (); ioctl (2, TIOCSPGRP, &pid); to change the process group on the terminal. Why would someone want to do this? -- Kevin Kleinfelter @ Management Science America, Inc (404) 239-2347 gatech!nanovx!msa3b!kevin
chris@mimsy.umd.edu (Chris Torek) (10/20/89)
In article <1158@msa3b.UUCP> kevin@msa3b.UUCP (Kevin P. Kleinfelter) writes: >What is a process group? The short answer is `something you should not use unless you know what it is' :-) >I know the following things: > > You can make a process the process group leader via setpgrp(); > (with some versions of UNIX) (SysV) > You can send a signal to all members of a process group Tty signals go to process groups. If you want to avoid tty signals you need to be in a different group, and/or not connected to the tty, and/or simply ignore the signals (a la `nohup'). The rest of the situation is system-dependent, so that the question cannot be answered without knowledge as to the specific Unix variant. -- `They were supposed to be green.' In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163) Domain: chris@cs.umd.edu Path: uunet!mimsy!chris
cpcahil@virtech.UUCP (Conor P. Cahill) (10/20/89)
In article <1158@msa3b.UUCP>, kevin@msa3b.UUCP (Kevin P. Kleinfelter) writes: > I have inherited some code which does > pid = setpgrp (); > ioctl (2, TIOCSPGRP, &pid); > to change the process group on the terminal. Why would someone want to > do this? The main purpose for changing the process group (and disconnecting from the tty -- the ioctl()) is to allow a background/daemon process to continue running without being affected by operations happening on the tty from which the process started. Like the user loggin out, which will normally send a SIGHUP to all processes associated with the terminal. -- +-----------------------------------------------------------------------+ | Conor P. Cahill uunet!virtech!cpcahil 703-430-9247 ! | Virtual Technologies Inc., P. O. Box 876, Sterling, VA 22170 | +-----------------------------------------------------------------------+