alternatives.txt

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update-alternatives:

interactive:

update-alternatives --config name


modes
------

--install $alink,$name,$apath,$apriority,@ARGV
--remove $name,$apath,@ARGV
--display $name


options
-------
--slave$ $slink,$sname,$spath,@ARGV

        $aslavelinkcount{$slink}++ && &badusage("slave link $slink duplicated");
        $aslavelink{$sname}= $slink;
        $aslavepath{$sname}= $spath;

--altdir $altdir

--admindir $admindir





Format of /var/lib/dpkg/alternatives/$name:

-------
"auto"|"manual"
link
(sname
 slink)*

(version
 priority
 spath* (so viele wie oben snames)
)*


link => $link

(sname,slink)s => @slavenames, @slavelinks

(version,priority,spath*) => $versions[lfd.Nr.],
                             $priorities[lfd.Nr.],
                             $slavepath{lfd.Nr., spathnr}

lfd.Nr. für version v steht in $versionnum{v}



--install $alink,$name,$apath,$apriority,@ARGV {
    rename_mv($link,$alink);  # d.h. alink mit link identifiziert
    $link= $alink;

    lfd.Nr. := $versionnum{$apath}; # d.h. apath mit version identifiziert
}



===========================

[root@tick /]# cat /var/lib/dpkg/alternatives/www-browser 
manual
/usr/bin/www-browser
www-browser.1.gz
/usr/share/man/man1/www-browser.1.gz

/usr/bin/w3m
25
/usr/share/man/man1/w3m.1.gz
/usr/bin/links.main
40
/usr/share/man/man1/links.main.1.gz
/usr/bin/lynx
50
/usr/share/man/man1/lynx.1.gz

[root@tick /]# 


==> in update-alternatives:

$manual="manual"
$link="/usr/bin/www-browser"
@slavenames = ("www-browser.1.gz")
$slavenum{"www-browser.1.gz"} = 1
$slavelinkcount{"/usr/share/man/man1/www-browser.1.gz"} = 1
@slavelinks = ("/usr/share/man/man1/www-browser.1.gz")


@versions = ("/usr/bin/w3m","/usr/bin/links.main", "/usr/bin/lynx")

$versionnum{"/usr/bin/w3m"} = 1
$priorities[1] = 25
$slavepath{1,0} = "/usr/share/man/man1/w3m.1.gz"
           ^ ^
           | |
 $versionnum index in @slavenames

$versionnum{"/usr/bin/links.main"} = 2
$priorities[2] = 40
$slavepath{2,0} = "/usr/share/man/man1/links.main.1.gz"

$versionnum{"/usr/bin/lynx"} = 3
$priorities[3] = 50
$slavepath{3,0} = "/usr/share/man/man1/lynx.1.gz"
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