[conspire] debian package

[Rick Moen]

Quoting Paul Zander (paulz at ieee.org):

> I am trying to use a math package called gmsh.  I am using Debian testing.
[...]
> Is there a "not too complicated" way to update this one package from >
> testing to unstable?  Or is this not advisable?  

Current testing version is 2.12.0+dfsg1-2+b1 .  Dependencies:
libc6 (>= 2.14)
libgcc1 (>= 1:3.0)
libgmsh2v5
libopenmpi1.10 
libstdc++6 (>= 5.2)
mpi-default-bin

https://packages.debian.org/stretch/gmsh

Current unstable version is 2.13.1+dfsg1-1 .  Dependencies:
libc6 (>= 2.14) 
libgcc1 (>= 1:3.0)
libgmsh2v5 
libopenmpi1.10 
libstdc++6 (>= 5.2) 
mpi-default-bin

https://packages.debian.org/sid/gmsh

So, exact same package dependencies.  (I'm assuming amd64 arch.)  So:

$ su -
# cd /tmo
# wget http://ftp.us.debian.org/debian/pool/main/g/gmsh/gmsh_2.13.1+dfsg1-1_amd64.deb
## That's from taking the 'amd64' link on
## https://packages.debian.org/sid/gmsh, and picking the direct download.
# dpkg -i gmsh_2.13.1+dfsg1-1_amd64.deb

In general, there is very little difference in versioning, often no
difference at all, between the contents of testing and that of unstable.
After all, they differ only by the selectivity of a quarantining script.

It's pretty safe to grab packages out of unstable and install them on
testing.  If you'd like to be able to do that on an ongoing basis, use
pinning.  That is, have _both_ testing and unstable in sources.list 
(or /etc/apt/sources.list.d/*), but use pinning to ensure that packages
from unstable will never be fetched unless you invoke that track
explcitly using '-t unstable', like:

# apt-get  -t unstable  install blahblahblah

See:
https://wiki.debian.org/AptPreferences#Pinning
or 
'man 5 apt_preferences'

By contrast, there is generally a _huge_ gap in package versioning
between Debian-stable and either testing or unstable, and I discourage
trying to mix in either of the latter two into Debian-stable:  If on
stable, use backports, instead of attempting to borrow from testing or
unstable.