Buck requires python 2.7

So although it’s advertised as buck supporting python 2.6 and 2.7, I’ve just found out it’s not the case.

In https://github.com/facebook/buck/blob/master/programs/buck_repo.py#L10 you’re using

from subprocess import check_output

which is not available in 2.6. So I am ok using 2.7 for python. But the issue is that I cannot force buck to pick up Python 2.7 from my system. Buck’s bin file is written in a way that makes it impossible https://github.com/facebook/buck/blob/master/bin/buck#L21

PYTHON=$(command -v python2 python | head -1)

On my system python2 is of version 2.6 coming from /usr/bin/python2, and python is of version 2.7 coming from a custom installed location. But you’re using command which skips over my PATH and chooses first python2, which is 2.6 and now my builds are broken with

~/Desktop/downloads/buck $ ./bin/buck --help
Traceback (most recent call last):
  File "/local/home/user/Desktop/downloads/buck/bin/../programs/buck.py", line 48, in <module>
    propagate_failure(main(sys.argv))
  File "/local/home/user/Desktop/downloads/buck/bin/../programs/buck.py", line 36, in main
    with get_repo(project) as buck_repo:
  File "/local/home/user/Desktop/downloads/buck/bin/../programs/buck.py", line 25, in get_repo
    from buck_repo import BuckRepo
  File "/local/home/user/Desktop/downloads/buck/programs/buck_repo.py", line 10, in <module>
    from subprocess import check_output
ImportError: cannot import name check_output

[yiding]

Fixed in b2af4022fe7168a4a31571a771ebda426af702eb.

[hey99xx]

@yiding sorry if I misunderstood command’s explanation from a coworker. It may be using PATH which is fine. But the thing is buck would choose python 2.6 regardless. On my system:

$ command -v python2 python
/usr/bin/python2
/mycustomlocation/python

$ /usr/bin/python2 --version
Python 2.6.9

$ /mycustomlocation/python --version
Python 2.7.8

which means PYTHON=$(command -v python2 python | head -1) will always be Python 2.6, unless I hack around my system and create a python2 symlink and point it to 2.7. But Python 2.6 came out of the box in my Linux, so I’m hesitant to modify my path to use Buck. As a temporary workaround, I’ve rewritten that line as PYTHON=$(command -v python | head -1) so I can keep building my dependent projects.

Thanks for the quick look at this issue.