[Fedora-livecd-list] pre-install scripts and syslinux

[David Straub]

On Wed, Nov 12, 2008 10:34 PM Jeremy Katz <katzj at redhat.com> wrote:
>The main reason has been that there are ... interesting questions about
>the environment it should run in.  What are you using them for and maybe
>that's enough to talk me into it :-)

  Since pykickstart already handles pre-install scripts, I pretty much just
copied the imgcreate functions that deal with the post-install scripts for
consistency.  I suppose this is the important function:

>     def __run_pre_scripts(self):
>         for s in kickstart.get_pre_scripts(self.ks):
>             (fd, path) = tempfile.mkstemp(prefix = "ks-script-",
>                                           dir = "/tmp")
> 
>             os.write(fd, s.script)
>             os.close(fd)
>             os.chmod(path, 0700)
> 
>             env = self._get_pre_scripts_env(s.inChroot)
> 
>             env["INSTALL_ROOT"] = self._instroot
>             preexec = None
>             script = path
> 
>             try:
>                 subprocess.call([s.interp, script],
>                                 preexec_fn = preexec, env = env)
>             except OSError, (err, msg):
>                 raise CreatorError("Failed to execute %%pre script "
>                                    "with '%s' : %s" % (s.interp, msg))
>             finally:
>                 os.unlink(path)
>

  I have this called as the first action in the install function, just before
yum runs.  I think the only changes I made to this from the post function are
that I removed the chroot conditional (since %pre is always --nochroot), and
that it writes the temporary script files to the system's /tmp rather than the
image's /tmp (since it doesn't exist at this point).

  What were the concerns regarding the environment?  All I needed was the
ability to get at a shell in the install image before yum is called, which is
all that does.

 Thanks,
  Dave