Bug#679010: dpkg: update-alternatives has no option to get name of master link

Package: dpkg
Version: 1.16.3
Severity: normal

Dear Maintainer,

To use update-alternatives --install <master link> <name> <path> <pri> ..., one needs an option
in update-alternatives to find the master link if <name> has just one alternative installed.
This is the symbolic link that points to the /etc/alternatives/<name>

For example, suppose one wants to install a new alternative to 'rename':
jack@berkeley:tmp => ls -lt /etc/alternatives/rename
0 lrwxrwxrwx 1 root root 16 Jan 15 17:04 /etc/alternatives/rename -> /usr/bin/prename

There is no option in update-alternatives to find the master link that points to /etc/alternatives/rename:

jack@berkeley:tmp => update-alternatives --config rename
There is only one alternative in link group rename: /usr/bin/prename
Nothing to configure.

jack@berkeley:tmp => update-alternatives --display rename
rename - auto mode
link currently points to /usr/bin/prename
/usr/bin/prename - priority 60
slave rename.1.gz: /usr/share/man/man1/prename.1.gz
Current 'best' version is '/usr/bin/prename'.

The only workaround is to look at the /var/lib/dpkg/alternatives file:
jack@berkeley:tmp => cat /var/lib/dpkg/alternatives/rename
auto
/usr/bin/rename <<<<<<<< this is needed for new install <<<<<<
rename.1.gz
/usr/share/man/man1/rename.1.gz

/usr/bin/prename
60
/usr/share/man/man1/prename.1.gz

jack@berkeley:tmp => ls -lt /usr/bin/rename
0 lrwxrwxrwx 1 root root 24 Jan 15 17:04 /usr/bin/rename -> /etc/alternatives/rename*

If update-alternatives is the interface to the alternatives system, it should provide the all information
needed to install a new alternative in all cases.

This fails if there is exactly one alternative installed but works if multiple alternatives are installed:
jack@berkeley:tmp => update-alternatives --config java
There are 5 choices for the alternative java (providing /usr/bin/java). <<<<<<<< this is needed for new install <<<<<<

Selection Path Priority Status

0 /usr/lib/jvm/java-6-openjdk-i386/jre/bin/java 1061 auto mode
1 /usr/bin/gij-4.6 1046 manual mode
2 /usr/lib/jvm/java-6-openjdk-i386/jre/bin/java 1061 manual mode
3 /usr/lib/jvm/java-6-sun/jre/bin/java 63 manual mode
4 /usr/lib/jvm/java-7-openjdk-i386/jre/bin/java 1051 manual mode
* 5 /usr/local/sun-java/jre1.7.0_05/bin/java 64 manual mode






Debian Release: wheezy/sid
APT prefers testing
APT policy: (500, 'testing')
Architecture: i386 (i686)

Kernel: Linux 3.1.0-1-686-pae (SMP w/6 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages dpkg depends on:
ii libbz2-1.0 1.0.6-1
ii libc6 2.13-24
ii libselinux1 2.1.0-4
ii tar 1.26-4
ii xz-utils 5.1.1alpha+20110809-3
ii zlib1g 1:1.2.3.4.dfsg-3

dpkg recommends no packages.

Versions of packages dpkg suggests:
ii apt 0.9.6

/etc/dpkg/dpkg.cfg changed:
refuse-downgrade
no-debsig
log /var/log/dpkg.log





To UNSUBSCRIBE, email to debian-bugs-dist-REQUEST@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org