"Douglas A. Tutty" <dtu...@vianet.ca> writes: > On Mon, Jun 22, 2009 at 08:17:44PM -0400, Kamaraju S Kusumanchi wrote: > >> Currently I have a shell script that works as below. >> 1) launch proga, progb in the background using nohup. >> 2) Ask proga, progb to write a file when they finish. >> 3) Every five minutes check if these files are present. If they are present, >> launch progc. >> >> This gets me going for now. But it looks terribly inefficient. I would >> appreciate if someone can provide a better solution. > > While you may think its terribly inefficient, it isn't really. A fancy > "wait" function is just polling anyway, you're just making it overt.
Just to clarify, wait(2) and the shell wait builtin do not poll, they instruct the kernel to put the process to sleep until a child process finishes, then wake it up and return from the wait call. Because of that they are very efficient. Still, if the programs in question are doing a great deal of work, the extra work required by polling will not be very significant in comparison. -----Scott. -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
