How to get the list of options that Python was compiled with?

Question

You can compile Python in various ways. I'd like to find out with which options my Python was compiled.

Concrete use-case: was my Python compiled with readline? I know I can see this by doing "import readline", but I'd like to see a list of compilation setting for my Python binary.

Edit: I mean the Python executable and not source code written by myself.

Answer 1

To build on mirk's answer, to find the configure flags that were actually used during the build, the value you're looking for is CONFIG_ARGS.

For example, this is the output for an Ubuntu-compiled Python:

>>> print distutils.sysconfig.get_config_var('CONFIG_ARGS')
'--enable-shared' '--prefix=/usr' '--enable-ipv6'
'--enable-unicode=ucs4' '--with-dbmliborder=bdb:gdbm'
'--with-system-expat' '--with-system-ffi' '--with-fpe ctl'
'CC=x86_64-linux-gnu-gcc' 'CFLAGS=-D_FORTIFY_SOURCE=2 -g
-fstack-protector --param=ssp-buffer-size=4 -Wformat
-Werror=format-security ' 'LDFLAGS=-Wl,-Bs ymbolic-functions
-Wl,-z,relro'

Answer 2

There is a module to see the system config

import sysconfig
print(sysconfig.get_config_vars())

It offers an interface to get individual variables as well.

sysconfig.get_config_var('HAVE_LIBREADLINE')

It is also accessible via shell:

python3 -m sysconfig | less

Edit:

before python2.7, you have to use

import distutils.sysconfig
print distutils.sysconfig.get_config_vars()

Answer 3

And another way to do it... Python supplies scripts per installed version...

  ls -l /usr/bin/python*config*
    16 Dec 21  2013 /usr/bin/python-config     -> python2.7-config
    16 Dec 21  2013 /usr/bin/python2-config    -> python2.7-config
    33 Mar 22 18:57 /usr/bin/python2.7-config  -> x86_64-linux-gnu-python2.7-config
    16 Mar 23 03:17 /usr/bin/python3-config    -> python3.4-config
    33 Apr 11 09:15 /usr/bin/python3.4-config  -> x86_64-linux-gnu-python3.4-config
    34 Apr 11 09:15 /usr/bin/python3.4m-config -> x86_64-linux-gnu-python3.4m-config
    17 Mar 23 03:17 /usr/bin/python3m-config   -> python3.4m-config

  python3-config --help
  Usage: /usr/bin/python3-config --prefix|--exec-prefix|--includes|--libs|--cflags|--ldflags|--extension-suffix|--help|--abiflags|--configdir

  python3-config --prefix
  /usr

The answers from one of my systems are:

--prefix           /usr
--exec-prefix      /usr
--includes         -I/usr/include/python3.4m -I/usr/include/python3.4m
--libs             -lpthread -ldl  -lutil -lm  -lpython3.4m
--cflags           -I/usr/include/python3.4m -I/usr/include/python3.4m  -Wno-unused-result -Werror=declaration-after-statement -g -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security  -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes
--ldflags          -L/usr/lib/python3.4/config-3.4m-x86_64-linux-gnu -L/usr/lib -lpthread -ldl  -lutil -lm  -lpython3.4m -Xlinker -export-dynamic -Wl,-O1 -Wl,-Bsymbolic-functions
--extension-suffix @SO@
--abiflags         m
--configdir        /usr/lib/python3.4/config-3.4m-x86_64-linux-gnu

So if you need setting values for bash scripts and such, these are available with this command line utility.

Answer 4

Here is a command that i use to compare different python configurations. It includes getting the value of the outputs:

$ python3.6 -c "import sysconfig;print('{}'.format('\n'.join(['{} = {}'.format(v, sysconfig.get_config_var(v)) for v in sorted(sysconfig.get_config_vars(), key=lambda s: s.lower())])))" > /tmp/python36.conf

$ python2.7 -c "import sysconfig;print('{}'.format('\n'.join(['{} = {}'.format(v, sysconfig.get_config_var(v)) for v in sorted(sysconfig.get_config_vars(), key=lambda s: s.lower())])))" > /tmp/python27.conf

$ sdiff /tmp/python36.conf /tmp/python27.conf

$ # This is my own version of colorized side-by-side diff from
$ # https://github.com/jlinoff/csdiff
$ csdiff /tmp/python36.conf /tmp/python27.conf