Bug #1403: Process.daemon should do a double fork to avoid problems with controlling terminals

• Status: Closed
• Assignee: -
• Target version: 1.9.2
• ruby -v: ruby 1.9

[gwright (Gary Wright)]

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Standard practice when 'daemonizing' is to do a second fork so that the final process is no longer a session leader and therefore can't acquire a new controlling terminal.

See Stevens, Advanced Programming in the Unix Environment for details.
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[nobu (Nobuyoshi Nakada)]

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Hi,

At Sat, 25 Apr 2009 08:06:36 +0900,
Gary Wright wrote in [ruby-core:23305]:

Author: Gary Wright
Status: Open, Priority: Normal
ruby -v: ruby 1.9.0 (2008-07-25 revision 18217) [i686-darwin9]

Standard practice when 'daemonizing' is to do a second fork
so that the final process is no longer a session leader and
therefore can't acquire a new controlling terminal.

See Process.setsid. Process.daemon implies it.

And daemon(3) is deprecated on Darwin.

--
Nobu Nakada

=end

[nobu (Nobuyoshi Nakada)]

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Hi,

At Sat, 25 Apr 2009 09:52:46 +0900,
Gary Wright wrote in [ruby-core:23307]:

Author: Gary Wright
Status: Open, Priority: Normal
ruby -v: ruby 1.9.0 (2008-07-25 revision 18217) [i686-darwin9]

Standard practice when 'daemonizing' is to do a second fork
so that the final process is no longer a session leader and
therefore can't acquire a new controlling terminal.

See Process.setsid. Process.daemon implies it.

setsid is not sufficient. That makes the child process a session
leader, establishes a new process group, and breaks the association
with the controlling terminal, but it doesn't prevent the process from
acquiring a controlling terminal if it should happen to open a tty
device (generally on system V based systems, BSD systems are different).

Then `i686-darwin9' is irrelevant at all?

The second fork ensures that the process (the grandchild of the
original process) is no longer a session leader and therefore can't
acquire a controlling terminal by opening a tty device.

Could you show concrete example?

--
Nobu Nakada

=end

[nobu (Nobuyoshi Nakada)]

• Category set to core
• Target version set to 1.9.2
• ruby -v changed from ruby 1.9.0 (2008-07-25 revision 18217) [i686-darwin9] to ruby 1.9

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=end

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

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Applied in changeset r23280.
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