Linux – Arch Linux: python and python2 are in conflict

If you don't need the python packages for all users then you can install them in your home like this:

pip install --user packagename

Installing in your home will not conflict with the package manager.

By default pip install --user will install in your "user site" directory. Usually that is something like: /home/lesmana/.local/lib/python3.6/site-packages.

The following command will print, among others, your "user site" location:

python -m site

To customize the install location:

PYTHONUSERBASE=$HOME/some/dir pip install --user packagename

this will install everything under $HOME/some/dir

to run:

PYTHONUSERBASE=$HOME/some/dir $HOME/some/dir/bin/progname

See the pip manual for more information.

if you do want the python package for all users then the best place to install it is /opt. for example like this:

PYTHONUSERBASE=/opt/packagedir pip install packagename

(note the missing --user)

and to run, as above:

PYTHONUSERBASE=/opt/packagedir /opt/packagedir/bin/progname

Background explanation: /opt is commonly acknowledged by gnu/linux distributions as the directory where the local user or system administrator can install his own stuff. in other words: the package manager of distributions usually do not touch /opt. this is more or less standardized in the Filesystem Hierarchy Standard

For comfort for the users you will still want to write a wrapper script and place it in /bin or /usr/bin. This still bears risk of colliding with the distribution package manager but at least it is just one wrapper script file. So the damage that might be done is minimal. You can name the wrapper script something like local-foo or custom-foo to further minimize the risk of collision with the distribution package manager.

Alternatively you can modify PATH to include /opt/bin and place your wrapper script there. But this again requires you to modify a (or some) system files where PATH is defined which again may be overwritten by the distribution package manager.

In short: if you want to install for all users then do so in /opt. Where you place the wrapper script for comfort is a judgement call.

More Information about /opt and Filesystem Hierarchy Standard:

• What is the difference between /opt and /usr/local?
• http://www.pathname.com/fhs/2.2/fhs-3.12.html

Download all these packages (I took the CentOS 6.6 versions from rpmfind.net)

nss-3.16.1-14.el6.x86_64.rpm
nss-util-3.16.1-3.el6.x86_64.rpm
nss-softokn-3.14.3-17.el6.x86_64.rpm
nss-softokn-freebl-3.14.3-17.el6.x86_64.rpm
nss-tools-3.16.1-14.el6.x86_64.rpm
nss-sysinit-3.16.1-14.el6.x86_64.rpm

and install them all in one go with rpm -Uvh nss-*.rpm.

That satisfies the dependencies of p11-kit-trust that yum couldn't figure out how to resolve on its own.

After that, yum update can update ca-certificates and install p11-kit-trust (for dependencies).