Re: Safest way to set python3 as default for `python`
Stuart Prescott writes: > There's a reasonable number of things in /usr/bin with "#!/usr/bin/env > python" that would be unhappy with this configuration. I don't think binaries in /usr/bin should be using "#!/usr/bin/env python". These will also break with virtualenvs. Packaged programs in Debian should be using /usr/bin/python*. Having said that, I can confirm you are correct, this does appear to be common. -- Brian May
Re: Safest way to set python3 as default for `python`
Ben Finney wrote: > To have a command with custom behaviour, the recommendation is the > general one: put an executable file at ‘/usr/local/bin/python’ with > whatever behaviour you want. eeek, please don't! If a user created an incompatible /usr/local/bin/rm (didn't delete files, didn't exit 0), that would break a lot of tools and we'd tell the user not to do that. Fortunately, users don't tend to. /usr/local/bin/python is no different but for some reason users feel they can meddle with it. Do not put locally versions of system tools like 'python' in root's PATH (or indeed in any user's PATH if the user expects to be able to run packaged tools). Doing so ends up potentially breaking packaged modules (they can find the wrong versions of dependencies in /usr/local since that is also in sys.path), and packaged applications (broken modules plus perhaps now running with the wrong version of the interpreter which is either incompatible or doesn't have the necessary modules installed). There's a reasonable number of things in /usr/bin with "#!/usr/bin/env python" that would be unhappy with this configuration. We have lots of experience of this sort of breakage in #debian, where we see the this breaking maintainer scripts or packaged tools. As soon as we see a python backtrace with /usr/local in it, we know that is going to be the problem and expunging the local python installation from /usr/local is what is needed. Putting python in other places such as /opt or ~/.local would be fine; even better still is to use one of the many virtualenv approaches so you're not even leaking that incompatible interpreter into a user's default environment. (see also: please don't run pip as root) cheers Stuart -- Stuart Prescotthttp://www.nanonanonano.net/ stu...@nanonanonano.net Debian Developer http://www.debian.org/ stu...@debian.org GPG fingerprint90E2 D2C1 AD14 6A1B 7EBB 891D BBC1 7EBB 1396 F2F7
Re: Safest way to set python3 as default for `python`
Bastian Venthur writes: > sorry if this question has been asked before. What is the currently > recommended way to make `python` point to `python3`? I'd like to have > it set on a system default level if possible. At a system default level, in Debian, the command ‘python’ (if it is installed) invokes the default Python 2 interpreter. Based on existing discussions I am confident there will not be a recommendation for a ‘python’ command to invoke anything except the default Python 2 interpreter, until long after Debian ceases support for Python 2 — and there is no current plan to drop Python 2 support in Debian. If you want a ‘python’ command at the system default level with different behaviour from that today, that's going against recommendations so I think you won't find a recommended way to have different behaviour. To have a command with custom behaviour, the recommendation is the general one: put an executable file at ‘/usr/local/bin/python’ with whatever behaviour you want. -- \ “But Marge, what if we chose the wrong religion? Each week we | `\ just make God madder and madder.” —Homer, _The Simpsons_ | _o__) | Ben Finney
Re: Safest way to set python3 as default for `python`
Hi Matthias, thanks for the reply and the explanation. Cheers, Bastian
Re: Safest way to set python3 as default for `python`
On 16.07.2018 09:44, Bastian Venthur wrote: Hi, sorry if this question has been asked before. What is the currently recommended way to make `python` point to `python3`? I'd like to have it set on a system default level if possible. There is none. Maybe in the far future when Debian doesn't ship a python command anymore, and doesn't rely on a python binary anymore, you can screw up your system as you like. But until that, don't mess around with the python symlink.
Re: Safest way to set python3 as default for `python`
On Mon, Jul 16, 2018 at 09:44:00AM +0200, Bastian Venthur wrote: > sorry if this question has been asked before. What is the currently > recommended way to make `python` point to `python3`? I'd like to have it set > on a system default level if possible. We don't recommend it so there is none AFAIK. -- WBR, wRAR signature.asc Description: PGP signature
Safest way to set python3 as default for `python`
Hi, sorry if this question has been asked before. What is the currently recommended way to make `python` point to `python3`? I'd like to have it set on a system default level if possible. Cheers, Bastian -- Dr. Bastian Venthur http://venthur.de Debian Developer venthur at debian org
