Is Python Installed?

[DaveMc]

Good morning,

I am new to the group and have a question I am hoping everyone can help with. I am working on a application and want to find out if there is a way at the initial run of the app, to check and see if Python is installed on a users system before it loads, regardless of if it is Windows, Mac or Linux?

Any help would be appreciated

[Axel_Erfurt]

On Mac and Linux you can use

which python3

or

command -v python3

[DaveMc]

On Mac and Linux you can use

which python3

or

command -v python3

Thank you Axel, that is a big help. I appreciate your response

[ndc85430]

Of course, which should return 0 if the program exists and non-zero if it can't find it, as is the convention on UNIX.

[Axel_Erfurt]

Of course, which should return 0 if the program exists and non-zero if it can't find it, as is the convention on UNIX.

In Linux which returns the path of the executable

Output:
axel@SamsungSA-11:/tmp$ which python3
/usr/bin/python3

[ndc85430]

By "return", I meant the exit code of the program, which in Bash, is stored in $?:

Output:
$ which gcc
/usr/bin/gcc
$ echo $?
0
$ which foobar
which: no foobar in (/usr/lib64/go1.11.4/go/bin:/usr/local/bin:/usr/bin:/bin:/usr/games:/usr/lib64/java/bin:/usr/lib64/java/jre/bin:/usr/lib64/kde4/libexec:/usr/lib64/qt/bin:/usr/share/texmf/bin:/usr/local/heroku/bin)
$ echo $?
1

Obviously if you're doing this in a Python program (e.g. using subprocess), there will be a way to obtain the return value so you can test it.

[buran]

Hm, if python program runs, obviously the python is installed. And if it is not installed, there is no way that a "running" python program would check if python is installed :-) it will just fail to execute it ($ python your_program.py)

now, you can check if some third-party package required is installed (or to be more precise - handle the error if it is not installed).

If your goal is to ship your program without need for end user to install python, there are plenty of options - compile it to binary executable, ship python interpreter bundled in the distribution, use containerization (Docker), etc.