Develop Reference

centOS 7 - difficulties with installing Python 3

I have a brand new centOS 7 VM that am trying to install Python 3 (currently 3.6.0) on. I am following a guide from Daniel Eriksson (https://danieleriksson.net/2017/02/08/how-to-install-latest-python-on-centos/)
but I'm running into an Pemission denied error when running the make && make altinstall command.
The last section of the error I'm getting is here:
gcc -pthread -c -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -std=c99 -Wextra -Wno-unused-result -Wno-unused-parameter -Wno-missing-field-initializers -I. -I./Include -fPIC -DPy_BUILD_CORE -o Programs/_testembed.o ./Programs/_testembed.c
gcc -pthread -Wl,-rpath /usr/local/lib -Xlinker -export-dynamic -o Programs/_testembed Programs/_testembed.o -L. -lpython3.6m -lpthread -ldl -lutil -lm
# Substitution happens here, as the completely-expanded BINDIR
# is not available in configure
sed -e "s,#EXENAME#,/usr/local/bin/python3.6m," < ./Misc/python-config.in >python-config.py
# Replace makefile compat. variable references with shell script compat. ones; ->
LC_ALL=C sed -e 's,\$(\([A-Za-z0-9_]*\)),\$\{\1\},g' < Misc/python-config.sh >python-config
# On Darwin, always use the python version of the script, the shell
# version doesn't use the compiler customizations that are provided
# in python (_osx_support.py).
if test `uname -s` = Darwin; then \
cp python-config.py python-config; \
fi
if test "no-framework" = "no-framework" ; then \
/bin/install -c python /usr/local/bin/python3.6m; \
else \
/bin/install -c -s Mac/pythonw /usr/local/bin/python3.6m; \
fi
/bin/install: cannot create regular file ‘/usr/local/bin/python3.6m’: Permission denied
make: *** [altbininstall] Error 1
I don't usually work with Linux, so I'm not exactly sure where to look for or what to try next. Any help on this appreciated. Thank you

The issue is with the permission required when running the command to install the package.
Use
sudo make && sudo make altinstall
instead of:
sudo make && make altinstall

Cython: Compiling and Cannot Find Library Mac OSX 10.12

I am just getting started with Cython and am trying to compile a "Hello World" script. I am trying to use gcc -Os /User/Documents/Python/Test\ Python/helloCopy.c -I/Library/Frameworks/Python.framework/Versions/3.5/include/python3.5m -l, but I don't know what to add after the -l. Other forum pages say to "include -lpython2.7 (or whatever version of Python you're using) on the linker command-line" but that produces ld: library not found for -lpython3.5
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Should I be directing the -l to a particular folder?

I do not know what resource you're using, but this does not say anything about a -l flag. It suggests
cython -a helloCopy.pyx
This creates a yourmod.c file, and the -a switch produces an annotated html file of the source code. Pass the -h flag for a complete list of supported flags.
gcc -shared -pthread -fPIC -fwrapv -O2 -Wall -fno-strict-aliasing -I/usr/include/python2.7 -o helloCopy.so helloCopy.c
(Linux)
On macOS I would try to compile with
gcc -I/usr/bin/python -o helloCopy.so helloCopy.c
to use the standard version of Python.

installing cx_freeze on ubuntu

i have kubuntu 15.10 with python2.7 and python 3.4m installed
if i install cxfreeze with sudo apt-get cx_freeze it is installed with no issues but the problem is when i compile my python modules the are compiled for python2.7 not python 3
So i am trying to build cx_freeze from source and i am facing this error when i run sudo python3 setup.py build
here's the error
adding base module named weakref
running build
running build_py
running build_ext
x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict
prototypes -g -fstack-protector-strong -Wformat -Werror=format
security -D_FORTIFY_SOURCE=2 -fPIC -Ibuild/temp.linux-x86_64-3.4
I/usr/include/python3.4m -c source/bases/Console.c -o
build/temp.linux-x86_64-3.4/source/bases/Console.o
x86_64-linux-gnu-gcc -pthread build/temp.linux-x86_64
3.4/source/bases/Console.o -L/usr/lib/python3.4/config-3.4m-x86_64
linux-gnu -lpython3.4 -o build/lib.linux-x86_64
3.4/cx_Freeze/bases/Console -Xlinker -export-dynamic -Wl,-O1 -Wl,
Bsymbolic-functions -lpthread -ldl -lutil -lm -lrt -lexpat -L/usr/lib
-lz -lexpat -s
/usr/bin/ld: cannot find -lz
collect2: error: ld returned 1 exit status
error: command 'x86_64-linux-gnu-gcc' failed with exit status 1'

Install zlib1g-dev :
sudo apt install zlib1g-dev
then install cx_freeze for python:
pip install cx_freeze
I've tried that on Ubuntu 18.04 and Python 3.6 and worked.

I had exactly the same problem. As suggested in this answer you just need to install the dependencies first:
pip3 install zlib1g-dev
Then sudo python3 setup.py build

How to embed particular version of python interpreter in c in OS X

I want to embed python in C. But I find that the version of python interpreter which is embedded in my program is 2.7 (The default version on mac).
How could I specify particular version of python interpreter when I compile the c codes in mac os x. The gcc in os x is definitely different from in linux.
I have already installed python3 through HomeBrew.
Thanks a lot.
UPDATE:
I try to use python3.4-config --cflags and python3.4-config --ldflags to find out the required compiler and linker flags. Then I get these recommended flags when compiling & linking:
-I/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/include/python3.4m -I/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/include/python3.4m -Wno-unused-result -Werror=declaration-after-statement -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -I/usr/local/include -I/usr/local/opt/sqlite/include
and
-L/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/lib/python3.4/config-3.4m -ldl -framework CoreFoundation -lpython3.4m
After this, I assemble these flags along with source file into gcc, and obtain an error:
Undefined symbols for architecture x86_64:
"_PyUnicodeUCS2_FromString", referenced from:
_main in py2-5d8da5.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
The C code which I test here comes from Python Documentation

I got the same errors when trying to do this tutorial on OSX. You don't need all of the flags that the config utility spits out. You definitely don't need the corefoundation framework if you're just doing the embedding tutorial. Just use the include directory for headers:
-I/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/include/python3.4m -I/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/include/python3.4m
, and the library to link to:
-L/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/lib/python3.4/config-3.4m -lpython3.4m
so here's a one-liner to compile and link:
gcc -I/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/include/python3.4m -I/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/include/python3.4m -L/usr/local/Cellar/python3/3.4.1/Frameworks/Python.framework/Versions/3.4/lib/python3.4/config-3.4m -lpython3.4m /path/to/main.c -o /path/to/output/executable

pip raises stdio.h not found error on Mac OS X Mavericks (10.9)

I have tried countless solutions at this point and nothing seems to work. I'm trying to install mysql-python, but this happens with numpy and other packages requiring gcc as well:
building '_mysql' extension
gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -isysroot /Developer/SDKs/MacOSX10.6.sdk -g -O2 -DNDEBUG -g -O3 -Dversion_info=(1,2,5,'final',1) -D__version__=1.2.5 -I/usr/local/mysql/include -I/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c _mysql.c -o build/temp.macosx-10.6-intel-2.7/_mysql.o -Os -g -fno-strict-aliasing -arch x86_64
In file included from _mysql.c:29:
/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7/Python.h:33:10: fatal error: 'stdio.h' file not found
#include <stdio.h>
^
1 error generated.
error: command 'gcc-4.2' failed with exit status 1
To point:
I have installed command line tools
Added symlink from /usr/bin/gcc to /usr/bin/gcc-4.2
gcc-4.2 --version
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
Target: x86_64-apple-darwin13.1.0
Thread model: posix
Created a dummy c file, successfully compiled, and ran it, so gcc itself is fine
$ cat a.c
#include <stdio.h>
main()
{
printf("hello\n");
}
$ gcc-4.2 a.c
a.c:3:1: warning: type specifier missing, defaults to 'int' [-Wimplicit-int]
main()
^~~~
1 warning generated.
$ ./a.out
hello
And for good measure,
$ xcode-select -p
/Library/Developer/CommandLineTools
What is going on?!
EDIT - Forgot to include python version
$ python
Python 2.7.2 (v2.7.2:8527427914a2, Jun 11 2011, 15:22:34)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
EDIT - Exciting development. Setting these variables makes some progress:
$ export CFLAGS="-arch i386 -arch x86_64"
$ export FFLAGS="-m32 -m64"
$ export LDFLAGS="-Wall -undefined dynamic_lookup -bundle -arch i386 -arch x86_64"
$ export CC=gcc-4.2
$ export CXX="g++ -arch i386 -arch x86_64"
However it fails again at
gcc-4.2 -bundle -undefined dynamic_lookup -isysroot /Developer/SDKs/MacOSX10.6.sdk -isysroot /Developer/SDKs/MacOSX10.6.sdk -g -Wall -undefined dynamic_lookup -bundle build/temp.macosx-10.6-intel-2.7/_mysql.o -L/usr/local/mysql/lib -lmysqlclient_r -o build/lib.macosx-10.6-intel-2.7/_mysql.so -arch x86_64
ld: library not found for -lSystem
clang: error: linker command failed with exit code 1 (use -v to see invocation)
error: command 'gcc-4.2' failed with exit status 1
I suspect it's a similar error having to do with command tools. Also, why is it using "/Developer/SDKs/MacOSX10.6.sdk" ? (excuse the noob questions, I'm trying to migrate from vim/unix to pycharm/mac and it's not going very well so far :( )

Starting from Mojave xcode-select --install is not enough, you should also install the package that can be found at /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg. Source: https://forums.developer.apple.com/thread/104296

As #wegry mentioned above--
brew install python
confirming with
$ which python
/usr/local/homebrew/bin/python
just made this entirely go away. Successfully installed numpy and mysql-python with pip!

This worked for me
xcode-select --install