easy way to create a daemon

[Joshua Zeidner]

On Wed, Mar 26, 2008 at 5:58 PM, Mike Schwartz <schwartz at acm.org> wrote:
>
> On Wed, Mar 26, 2008 at 3:55 PM, Walter J. Mack <wmack at componentsw.com> wrote:
>
>  > I remember on some systems that a "background" job would continue to run after logout, but only if it didn't try to output anything to stdin or stderr anymore (I believe that was true on AIX).
>  >
>  > The trick to get around that was to say
>  >
>  > command >&/dev/null&
>  >
>  > Walter
>  >
>  >
>  > Matt Graham wrote:
>  > After a long battle with technology, Joshua Zeidner wrote:
>  >
>  >
>  > On Wed, Mar 26, 2008 at 2:01 PM, Nathan <nathan at paysonlinux.org> wrote:
>  >
>  >
>  > On Wednesday 26 March 2008 13:59:59 Joshua Zeidner wrote:
>  >
>  >
>  > Is there an easy way to create a daemon without creating an init.d
>  > script, etc.?
>  >
>  > what I do is ssh into whichever box it is, even the local machine, and
>  > run the command with an & at the end, then exit. From there I can do
>  > whatever I want, except reboot and it will continue running.
>  >
>  > well the system I'm using appears to terminate a background (&)
>  > process when the user is logged out.
>  > The shell sends HUP to all its children when the shell exits. Hence nohup.
>  >
>  >
>  > I always thought that background processes are still children of the shell
>  > process, and thus terminating the shell will kill the &'d process, but I
>  > could be wrong on that one. I'm not sure if this is the default, or just
>  > how this Debian system was set up.
>  >
>  > Debian? Look into the start-stop-daemon program. That's a fairly simple way
>  > to make something that wasn't originally intended to be a daemon act somewhat
>  > like a daemon. I used this to run a couple of useful persistent scripts at
>  > boot time on a Debian box.
>  >
>  >
>  > Everything else on this server is super bolted down- so I would be surprised
>  > if [it's] not default.
>  >
>  > HUPping all children of the shell is standard behavior, not anything "super
>  > bolted down".
>  >
>
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>
>  I think there was a presentation on this topic,
>  at one of those "developer" meetings (held at Adtron in Tempe)
>  some time between Sept. 2006 and May 2007.
>     ...it included stuff about how the program / script could "fork"
>  itself and switch user IDs to no longer be associated with the
>  person who entered the command to cause it to start.
>     Someone else who understands [bash, and] this stuff
>  "better than I do" might chime in at this point;  especially
>  if the notes from that presentation are available on the web
>  or something.
>      ...actually, maybe I don't understand they key part --
>   the part about << "without creating an init.d script, etc.?" >>.

  Unless anyone wishes to discuss this topic beyond the scope of
scratching my personal itch, Jon's solution solved my problem
beautifully.  BTW, Mike your prose looks like FORTRAN code! :)

 -jmz




-- 

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