Re: updating context on Ubuntu 6.06

[Sanjoy Mahajan <sanjoy@mrao.cam.ac.uk>]

> > Whereas the "$@" form would produce
> > 
> >   texmfstart.rb "--option=hi there"
> > 
> > This second form is what you want, no?
> 
> Ah, I see. (is that bash-only?)

It was hard to find a machine not running bash, a measure of the
success of free software.  But I eventually found a nearby Solaris
machine running 'sh' (couldn't tell which version), but it's man entry
says the same:

     if $@ is within a pair of double quotes, the positional
     parameters are substituted and quoted, separated by unquoted
     spaces ("$1""$2" ... )

So I think it's safe, and increases robustness, to change $@ -> "$@"
in all the stub scripts.

> Would it not work to simply point the variable TEXMFLOCAL to
> ~/texmf?

I was a little leery but tried it.  Meanwhile here's a patch that
fixes the need for that:

--- a/scripts/context/ruby/ctxtools.rb	Wed Jul 26 14:50:16 2006 -0400
+++ b/scripts/context/ruby/ctxtools.rb	Wed Jul 26 14:53:57 2006 -0400
@@ -2314,7 +2314,7 @@ class Commands
         end
 
         def locatedlocaltree
-            return `kpsewhich --expand-var $TEXMFLOCAL`.chomp rescue nil
+            return `kpsewhich --expand-var '$TEXMFLOCAL'`.chomp rescue nil
         end
 
         def extractarchive(archive)

The only problem is that it'll now, as intended, use the TEXMFLOCAL
from texmf.cnf.  But TEXMFLOCAL is probably not ~/texmf, so you'll
still have to force the setting like this:

  TEXMFLOCAL=~/texmf texmfstart ctxtools --updatecontext

The next problem was this message during the update:

chmod: cannot access `scripts/context/unix/stubs/*': No such file or directory

For my second attempt at ruby programming (the first being the two
glorious quotes above), I looked to see what ctxtools.rb was doing
around the chmod.  It was supposed to report an error with this line:

 report("change x-permissions of '" + stubs + "' manually")

But the line was not executed, because it was in a ruby 'rescue' clause.
But when system("chmod +x ....") fails, it returns false, but does not
throw an exception for rescue.  So I rewrote the extractarchive()
function to wrap the system() calls in if/unless clauses rather than
rescue clauses.  In doing so I noticed why the chmod failed: the path
should be

  scripts/context/stubs/unix/*

rather than

  scripts/context/unix/stubs/*

The patch below does that change as well as the change of rescue ->
if/unless.  With these patches the automatic update went smoothly.

One question: How safe is it that the ctxtools.rb script is
overwritten by the unzip in the middle of running the script?  Will
ruby execute half from the old script and half from the new script?
It wasn't an issue for me, I eventually realized, because the -u
switch to unzip meant that my updated ctxtools.rb was not overwritten.
But in general it will be.


--- a/scripts/context/ruby/ctxtools.rb	Wed Jul 26 14:54:24 2006 -0400
+++ b/scripts/context/ruby/ctxtools.rb	Wed Jul 26 15:36:21 2006 -0400
@@ -2318,26 +2318,19 @@ class Commands
         end
 
         def extractarchive(archive)
-            if FileTest.file?(archive) then
-                begin
-                    system("unzip -uo #{archive}")
-                rescue
-                    report("fatal error, make sure that you have 'unzip' in your path")
-                    return false
-                else
-                    if System.unix? then
-                        begin
-                            system("chmod +x scripts/context/unix/stubs/*")
-                        rescue
-                            report("change x-permissions of 'scripts/context/unix/stubs/*' manually")
-                        end
-                    end
-                    return true
-                end
-            else
+            unless FileTest.file?(archive) then
                 report("fatal error, '{archive}' has not been downloaded")
                 return false
             end
+            unless system("unzip -uo #{archive}") then
+                report("fatal error, make sure that you have 'unzip' in your path")
+                return false
+            end
+            stubs = "scripts/context/stubs/unix/*"
+            if System.unix? and not system("chmod +x " + stubs) then
+                report("change x-permissions of '" + stubs + "' manually")
+            end
+            return true
         end
 
         def remakeformats