linux user group brescia

On Fri, 2003-12-19 at 09:50, Vernia Damiano wrote:

> 	Daccordo. Ma "non serve" solo a me o "non serve" anche agli altri? 

Se l'hanno messo, qualcuno lo userà, ma personalmente non l'ho mai
incontrato da nessuna parte.

> :-) Perche' mi e' gia' capitato di scrivere un programma per estrarre 
> delle colonne da un file di testo (e poi trovare "cut") oppure per 
> stampare degli interi scritti in binario in un file come colonna di numeri 
> (e poi scoprire "od")...

Nella info page (ma tu non ce l'hai? :) dicono questo:

`tsort': Background
===================
                                                                                                  
   `tsort' exists because very early versions of the Unix linker
processed an archive file exactly once, and in order.  As `ld' read
each object in the archive, it decided whether it was needed in the
program based on whether it defined any symbols which were undefined at
that point in the link.
                                                                                                  
   This meant that dependencies within the archive had to be handled
specially.  For example, `scanf' probably calls `read'.  That means
that in a single pass through an archive, it was important for `scanf.o'
to appear before read.o, because otherwise a program which calls
`scanf' but not `read' might end up with an unexpected unresolved
reference to `read'.
                                                                                                  
   The way to address this problem was to first generate a set of
dependencies of one object file on another.  This was done by a shell
script called `lorder'.  The GNU tools don't provide a version of
lorder, as far as I know, but you can still find it in BSD
distributions.
                                                                                                  
   Then you ran `tsort' over the `lorder' output, and you used the
resulting sort to define the order in which you added objects to the
archive.
                                                                                                  
   This whole procedure has been obsolete since about 1980, because
Unix archives now contain a symbol table (traditionally built by
`ranlib', now generally built by `ar' itself), and the Unix linker uses
the symbol table to effectively make multiple passes over an archive
file.
                                                                                                  
   Anyhow, that's where tsort came from.  To solve an old problem with
the way the linker handled archive files, which has since been solved
in different ways.
                                                                                                  
Giudica tu...


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