Hello Daniel,
Daniel Drake a écrit :
I guess that depends on your ability as a C programmer and your
definition of 'flexible'. As shell interpreters are typically written
in C I don't think you can fairly say that you can do things in shell
script which can't be done in C.
First, i didn't want to hurt and i'm happy to see you like C but it
seems you misunderstood me :). C is just more powerful when you talk
about speed, pointers, functions and procedures. Anyway, C comes from C
and ... assembler. Assembler is also powerful but not flexible, mostly
because it depends on the hardware you use. It is difficult to read and
does not fit for large programs (what about Doom 1 the game ? ;).
Also we could talk about another "command interpreter" like irb. It
doesn't depend on any platforms or hardwares, it is object-oriented and
you can program while using it. That's what i call flexible. Of course
{ba,a,k,c,etc}sh are certainly just enough flexible but obviously not
powerful. You want more power, you can also write a program in C or in
whatever language you like and call it from the shell interpreter. As a
result, you will increase the abilities of your shell.
Imagine you lack some functionalities in your script. You just need to
add them and also rerun the script. Such flexibility is not possible
with C or Pascal especially if you don't have either libraries or
compilers. It is like in the past with a C64 where you could peek and
poke in basic in a program to cheat ! with C you have only {a,s}db like
debugger (it is a little bit more difficult then...) But indeed, a
script doesn't protect you from syntax errors. In that case you can even
not call a shell. You need the rescue cdrom as usual :)
baselayout-2 doesn't drop any features that I know about, actually it
adds several, and it is much much more reliable than its predecessors.
It solves all the highly reproducible and extremely difficult to fix
problems that I had with baselayout-1.
Sorry, i didn't go into baselayout-2 too deep but you write rc in C and
that is what i have considered a bad idea. You make approximately 11
calls to exec(). If something has changed like the name of a program it
calls, you won't be able to remedy it with ease (and don't tell me: just
create a link to it ;).
Yes, it is difficult to fix problems with a shell script but sometimes
that means the script has become too big and it is time to think it
differently.
I like the ideas in baselayout-1 but unfortunately i didn't have really
any use of it except the fact i can control the order the daemons are
loaded. Instead /sbin/functions.sh has helped me a lot to write a script
that does approximately the same but in ash and with candies too :). I
actually use it during the earlier boot stage process when disks are
still not recognized. Also i have integrated a modified
splash-functions.sh too. It is certainly not universal but it works. I
hope i will be able to support crypted raid1 boot disk as well in the
future. Also, it isn't fast nor it doesn't innovate, but above all it is
aesthetic (in my point of view anyway).
And believe me, I tried to fix them, focusing specifically on the
concurrency issues. I now believe it is *impossible* to write an
unbreakable and race-free locking mechanism in shell script, which is
the only realistic way to avoid some of these bugs.
Daniel
Right, a shell is not what handles the best concurrency issues but
"wait" and "jobs" have been quite improved. If you have an example i
could try. Also, that makes life exciting and i cheer you up. I'm sure
you will succeed and improve gentoo even better :)
| And unless you are missing some kind of feature from baselayout-2, or
there is otherwise something that could be done with previous
| versions that is no longer possible, then I don't think you have any
real reasons (other than political ones) to push off the upgrade...
I'm not quite good in politics but i will follow your advice :). I just
have feared you will definitely drop baselayout-1. (anyway, maintaining
two different kinds of software that do approximately the same thing is
a pain). I will need to reconvert sooner or later. Also, we leave in
really hard time, everything is moving too fast ;)
Jj
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