Re: building rc on QNX4

[Carlo Strozzi <carlos@linux.it>]

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On Mon, May 08, 2000 at 04:29:54AM -0400, Tim Goodwin wrote:
 >> A more important issue IMHO is whether Rc should provide a built-in
 >> read function, similar to the one offered by most Bourne shells;
 >
 >There is no *need* to make `read' a builtin: see the EXAMPLES file in
 >the distribution for an alternative.  One of rc's design goals is to
 >avoid unnecessary builtins.  So, no, I don't think this is likely to
 >happen.
 >

Unfortunately the example provided does not work the way 'read' does,
and is an extra-process that needs to be spawned for each input line.
                                                                     
 >> one is whether it will ever make it possible not to export everything to
 >> the environment by default.
 >
 >I brought this up a few months ago, and the consensus seemed to be that
 >the current scheme works well enough in practice.  Have you encountered
 >a problem?

hmm ... not really. Mine is just a general concern. Currently I
initialize every variable that I'm going to use in a script, right
at the beginning of the program, somewhat like what you do with C
whan you declare things first.  That is because unless I maintain a
global name-space I never know what a variable is going to contain 
when the program is called. Having a clean environment would
be desirable in general.

Anyway, the above is another minor issue, it may as well be that the
current scheme is ok. What I _really_ miss is a 'read', or 'line',  
function, for record-oriented input, and I think this feeling is
shared also by others. While things like 'test' are rarely called   
inside a loop, reading lines from a file is the opposite, and spawning
an external process on each line sucks, especially when one uses
the shell for writing Web CGI scripts, like I do.

Beside all that, I am a long-time (Bourne) shell user, and I whish I
had uncovered rc before :-)

Anyway, just to give my two-cent and not just ask for things :-), here
are a couple of functions to emulate often-used external processes like
basename(1) and dirname(1). I've tried to mimic the respective utilities
as closely as I could. Bug-fixes are welcome :-)

bye  -carlo
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#
# Emulate dirname(1)
#

fn DirName {
   ~ $1 () && { echo DirName: too few arguments >[1=2] ; return 1 }
   ~ $1 '' .* && { echo . ; return }
   ~ $1 / && { echo / ; return }
   x=() y=() {
      x = ``(/) {echo -n $1}
      ~ $1 /* && ~ $x(2) () && { echo / ; return }
      ~ $x(2) () && { echo . ; return } 
      * = $x
      while (!~ $#* 0 1) { y = $y/$1 ; shift }
      echo $y
   }
}

#
# Emulate basename(1)
#

fn BaseName {
   ~ $1 () && { echo BaseName: too few arguments >[1=2] ; return 1 }
   ~ $1 '' / && return
   x = () {
      x = ``(/) {echo -n $1}
      echo $x($#x)
   }
}

# End of stuff.