[Xquartz-dev] 2.3.2_rc4

[Cameron Simpson]

On 19Dec2008 08:17, Martin Costabel <costabel at wanadoo.fr> wrote:
> Cameron Simpson wrote:
>> On 19Dec2008 00:37, Martin Costabel <costabel at wanadoo.fr> wrote:
>>> I think the following works (does for me, anyway, but I haven\t 
>>> tested  it extensively):
>>> #!/bin/sh
>>> /usr/bin/login -pqf $USER <<EOF
>>>   $*
>>> EOF
>>
>> Please no. That completey mangles the command line if any of the
>> app command line arguments have spaces.
>
> Which app command line arguments are you talking about? I am targeting  
> specifically the startup procedure of X11 on Mac OS X Leopard, where the  
> command corresponding to $* in the above is typically something like
>
>   /Applications/Utilities/X11.app/Contents/MacOS/X11.bin -psn_0_716975

Maybe, it just grates to see something non-robust deployed.
Wrapper script (and the above _is_ a wrapper script) should preserve
their caller's arguments perfectly, not rely on the arguments typically
being what they expect.

> Do you have another suggestion how to fix Jeremy's current approach to  
> starting X11 on Leopard, so that it works for users who have tcsh as  
> their login shell?

Yep. [...]
>>> I wonder how Terminal.app is doing this. After all, it manages to 
>>> start  a login shell for everybody.
>>
>> Historically, if a shell is started with the first character of argv[0]
>> supplied as a dash then it runs as a login shell. That's how the magic
>> used to work; that way the caller doesn't need special per-shell
>> knowledge.
>
> How do you get that "-" into argv[0]? Are you suggesting that one should  
> write a wrapper in C instead of a shell script?

I used to do exactly that (not for login shells but for something else). It's
a tiny program and handy. However, it seems the login(1) command lets us
avoid that anyway, so...

What's wrong with this?

  #!/bin/bash
  : ${USER:=`id -un`}
  : ${SHELL:=/bin/sh}
  qcmd=
  for arg
  do  qcmd=$qcmd`printf " %q" "$arg"`
  done
  exec /usr/bin/login -pqf "$USER" "$SHELL" -c "$qcmd"

(That's bash instead of sh purely to use the %q printf extension.)
It correctly preserves command line strings while still using your
/usr/bin/login incantation to obtain the environment in a shell
independent manner.

It does rely on the shell accepting the -c command line option, but all
shells do that as otherwise they can't be used by programs with shell
escapes that hand off to the user's shell.

Comments?

>> Are we not spending a lot of effort in the wrong place?
>
> That may well be the case, but I don't see anyone spending any effort on  
> rewriting once again the whole startup procedure for X11 on Leopard.

Surely we're doing that right now:-)

Cheers,
-- 
Cameron Simpson <cs at zip.com.au> DoD#743
http://www.cskk.ezoshosting.com/cs/

... It beeped and said "Countdown initiated." Is that bad?