How do I install a specific version of duplicity. The one I have is duplicity 0.6.21 and the one I want is 0.6.18
I want to setup a new virtual machine with some specified packages (name and version), that are provided.  For example apache2 in version 2.2.20-1ubuntu1 with all dependencies. Even if there is a new version of this package on the servers this one should be installed.  The solution has to work/scale with multiple (n) "setups". Another virtual machine might need an older version of apache2.  I currently know of some possibilities that install the exact packages, but do not scale that good:   Copy all required *.deb to every virtual machine manually and enter: dpkg -i ... -> Could work, but it is very error prone. (Manual scripts etc.) Create and use a new Ubuntu repository for each setup. -> Does not work because I would need n repositories. Setup the machine once and copy the VM / create a snapshot. -> Does not work because I would need to store n VMs.   My problem could be labeled as patch management, but I do not want to update my packages to the current version. My goal is to install old packages.
Run command on another(new) terminal window How to run any command in another terminal window?  Example: I opened one terminal window and if I run command like apropos editor, then it run and out-puts on that window. But I want to run same command on another terminal window (new window) instead on present window from first terminal.   Further clarification:  I need suggest-command &lt;command&gt; that open new terminal window and run mentioned &lt;command&gt; in that (newly opened) window. (where suggest-command is example of suggestion of command.)  How to do that? Can I make `find` return non-0 when no matching files are found? How to resolve a hostname to an IP address in Metro/WinRT? Dublin transit visa requirements for Indian citizens What should I look for when buying chain lube / lubricant? In the past, I personally have only used WD-40.   However, I have occasionally had my bicycle looked over at the locally run, free service sessions and most of the mechanics there use a hand applied type of greasy gel (I forget the name).  Questions:   Is WD-40 suitable for bicycle chains? Would alternatives provide better chain longevity? When shopping around for lubricant, what are the most important things to look for? What do you use and why?  (optional added extra) Any tips for reducing chain wear? How to setup OpenVPN Client I'm trying to setup OpenVPN using NetworkManager. The GUI seems buggy and unresponsive. Are there any other tools for setting up a VPN client? How do I push amended commit to the remote Git repository? When I've worked a bit with my source code, I did my usual thing commit and then I pushed to a remote repository. But then I noticed I forgot to organize my imports in the source code. So I do the amend command to replace the previous commit:  &gt; git commit --amend   Unfortunately the commit can't be pushed back to the repository. It is rejected like this:  &gt; git push origin To //my.remote.repo.com/stuff.git/  ! [rejected]        master -&gt; master (non-fast forward) error: failed to push some refs to '//my.remote.repo.com/stuff.git/'   What should I do? (I can access the remote repository.) How to insert a very large number of records into a MySql database as fast as possible Op Amps: how do they know whether the supply is split? Most op amps can operate in single and split supply configurations. However, I cannot see how this is possible.  If I connect voltages \$V_\text{SY}^+\$ and \$V_\text{SY}^-\$ to the positive and negative supply pins of a op amp, and \$V_+\$ and \$V_-\$ to the non-inverting and inverting inputs, then the output is (if \$A_\text{OL}\$ is the open loop gain of the op amp): $$V_\text{out}=A_\text{OL}(V_+-V_-)+V_\text{SY}^-\tag{Single-supply}~\text{ }~~\text{ }~~\text{ }~~\text{ }~~\text{ }~~\text{ }$$ The above equation is from personal experience using op amps in single supply (i.e. \$V_\text{SY}^- = \text{GND}, V_\text{SY}^+ &gt; \text{GND}\$).  In split supply, we can use the following diagram from MIT's 6.002 introduction to electronics lecture video:  $$V_\text{out}=A_\text{OL}(V_+-V_-)+(V_\text{SY}^+-V_\text{SY}^-)/2\tag{Split-supply}$$  These two equations, however, are mutually inconsistent: If I take an op amp and hook up a single voltage source between its supply pins, how does the op amp know that the resulting voltage is not split between two sources?   It must know - but how does it know? Significance of the second focus in elliptical orbits Where did Schrödinger solve the radiating problem of Bohr's model? One of the problems with Bohr's theory to describe the hydrogen atom, was that the electron orbiting around the nucleus has an acceleration. Therefore it radiates and loses energy, until it would collapse with the nucleus.  Now Schrödinger describes the electron as a wave function. His theory is able to describe all atoms (in contrast to Bohr's model), but how is the radiation problem solved? I understand that the wave has not an exact position in the time anymore. But the electron still "moves", so it has an acceleration anyway (because of vibrations or so).   Why is in this theory the electron not radiating anymore? And if it is, why doesn't the atom collapse? How does the Schengen 90/180 rule work? I have a sequence $T_1,T_2,\ldots$ of independent exponential random variables with paramter $\lambda$. I take the sum $S=\sum_{i=1}^n T_i$ and now I would like to calculate the probability density function.  Well, I know that $P(T_i&gt;t)=e^{-\lambda t}$ and therefore $f_{T_i}(t)=\lambda e^{-\lambda t}$ so I need to find $P(T_1+\cdots+T_n&gt;t)$ and take the derivative. But I cannot expand the probability term, you have any ideas? Reapplying for a UK Standard Visitor visa after a refusal Let $F$ be a field and $f: \mathbb{Z} \to F$ be a ring epimorphism. How do I distinguish between a command, utility, or builtin for getting documentation? I'm running Bash scripting, but sometimes I get confused which of these commands I use belong to who. Sometimes man xxx works, sometimes doesn't, so I use --help or info, mostly one of these works to show description of the command. Can anyone tell me how I would know what command belongs to what? Bash builtin, GNU utility, etc. I heard myself saying something was "tickety-boo", meaning good, successful, or satisfactory. Does anyone know where this strange-sounding phrase originated? Can I run the python interpreter without generating the compiled .pyc files? Can I use Wi-Fi and cable (Ethernet) networking at same time? I am on an intranet that is not connected to the Internet and a Wi-Fi router with connection to the Internet. When I am connected to the wireless network, I can browse the Internet, but I cannot browse my LAN with my Ethernet cable connected.  How can I browse the Internet via my Wi-Fi router and at the same time browse my local LAN web application via my connected Ethernet cable? Finding the limit of $\frac {n}{\sqrt[n]{n!}}$