[Pkg-sysvinit-devel] Bug#339955: debian-policy: do not require /etc/init.d/*.sh scripts to be sourced

[Kel Modderman]

Package: debian-policy
Version: 3.8.0.1
Severity: wishlist

Hi Debian Policy maintainers,

It is the opinion of myself and Petter Reinholdtsen, maintainers of the
sysvinit package, that the last sentence of §9.3.1 of policy is no longer
relevant and should be removed:

"""Also, if the script name ends in .sh, the script will be sourced in
runlevel S rather than being run in a forked subprocess, but will be
explicitly run by sh in all other runlevels."""

The reasons for which it should be removed are:

* /etc/init.d/rc has not supported this for an extremely long time, probably
  never, because the system would be unbootable due to .sh scripts calling
  'exit' [0, 1].

* the reason why .sh scripts should be sourced is not clear. A popular
  theory is that it was an optimisation to avoid forking shells and reduce
  boot time [2]. It may have been an interface to allow scripts to "set
  an environment variable which would propogate through to subsequent
  scripts" [3].

  These days, sourcing .sh scripts instead of executing them is not so
  much of an optimisation; we have a lightweight shell dash which can be
  used as /bin/sh and has been measured to improve boot time [4]. startpar
  has been hacked on to work better with the Debian boot system and we hope
  to use it for parrallel execution of initscripts in the future without
  contradicting policy (it a C program which uses execlp() to execute
  scripts).

  Passing enviroment variables around by sourcing .sh scripts is not a
  supported interface: .sh scripts have not been sourced for years
  and nobody has cared.

* it would be nice to clean up /etc/init.d/rc in the absence of this
  requirement. Trying to support the sourcing of /etc/init.d/*.sh
  scripts makes the code much uglier to maintain.

Thanks, Kel.

[0] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=339955#59
[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=339955#120
[2] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=339955#20
[3] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=339955#15
[4] http://initscripts-ng.alioth.debian.org/soc2006-bootsystem/bootcharts.html