[issue10835] sys.executable default and altinstall

[Eryk Sun]

Eryk Sun  added the comment:

In 3.2, the default program name on non-Windows systems was changed to 
"python3" (see bpo-15020). In 3.5, the code was moved into Python/pylifecycle.c 
(see bpo-22869). Between 3.7 and 3.8, the initialization code was rewritten 
(see PEP 587). Currently it's set in config_init_program_name() in 
Python/initconfig.c. On POSIX systems, calculate_which() in Modules/getpath.c 
searches PATH to resolve the name if it has no path separator. For example:

$ bash -c 'exec -a "" python -c "import sys; print(repr(sys.executable))"'
'/home/someone/.local/bin/python3'

The default "python3" program name isn't used if C argv[0] is non-empty, in 
which case calculate_which() may or may not find the given program name:

$ bash -c 'exec -a "ls" python -c "import sys; print(repr(sys.executable))"'
'/usr/bin/ls'

$ bash -c 'exec -a "py" python -c "import sys; print(repr(sys.executable))"'
''

In Windows, the default program name is "python", but this isn't relevant for 
sys.executable, which is based on GetModuleFileNameW(NULL, ...) instead. This 
is similar to using readlink("/proc/self/exe", ...) in Linux, except the loader 
in Windows, and thus GetModuleFileNameW(), does not resolve symlinks in the 
file path.

--
nosy: +eryksun
status: pending -> open

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[Irit Katriel]

Irit Katriel  added the comment:

I can't reproduce this on 3.11, and I don't see a "progname" variable in 
Python/pythonrun.c.

I will close this unless someone will indicate it is still relevant.

--
nosy: +iritkatriel
resolution:  -> out of date
status: open -> pending

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[Éric Araujo]

Changes by Éric Araujo mer...@netwok.org:


--
versions: +Python 3.5 -Python 2.7, Python 3.1, Python 3.2

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[Piotr Dobrogost]

Piotr Dobrogost added the comment:

 Garbage in, garbage out.

In this case – exec -a '' – yes, but in general not so – see Mismatch between 
sys.executable and sys.version in Python question at SO 
(http://stackoverflow.com/q/22236727/95735).

As to not guessing Victor STINNER in comment 
http://bugs.python.org/issue7774#msg100849 wrote this:


There are different methods to get the real program name, but no one is 
portable. As flox wrote, we can do a best effort to provide a valid 
sys.executable. Extract of stackoverflow link:

 * Mac OS X: _NSGetExecutablePath() (man 3 dyld)
 * Linux: readlink /proc/self/exe
 * Solaris: getexecname()
 * FreeBSD: sysctl CTL_KERN KERN_PROC KERN_PROC_PATHNAME -1
 * BSD with procfs: readlink /proc/curproc/file
 * Windows: GetModuleFileName() with hModule = NULL


--
nosy: +piotr.dobrogost

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[Éric Araujo]

Changes by Éric Araujo mer...@netwok.org:


--
nosy: +eric.araujo

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[Stéphane Gaudreault]

Changes by Stéphane Gaudreault steph...@archlinux.org:


--
nosy: +stephane

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[Martin v . Löwis]

Martin v. Löwis mar...@v.loewis.de added the comment:

I fail to see the bug. Garbage in, garbage out. AFAIU, returning 
/usr/bin/python2.7 still might be the wrong answer.

--
nosy: +loewis

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[R. David Murray]

R. David Murray rdmur...@bitdance.com added the comment:

I agree that not guessing would be better.  But as long as we *are* guessing, 
it seems to me that /usr/bin/python2.7 would be less wrong than 
/usr/bin/python, for almost all modern unix systems.

--

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[Martin v . Löwis]

Martin v. Löwis mar...@v.loewis.de added the comment:

 I agree that not guessing would be better.

Well, on Linux, readlink(/proc/self/exe) would be better than
guessing.

--

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[Allan McRae]

New submission from Allan McRae al...@archlinux.org:

when sys.executable is run with a modified argv[0] such as:

 sh -c exec -a '' /usr/bin/python2.7 -c 'import sys; print(sys.executable)'

it returns some a hardcoded value.   In this case, it returns /usr/bin/python.  
 This value is likely wrong when python is installed with make altinstall.

A possible solution is to modify the progname variable in Python/pythonrun.c 
to include the version in it so that the hardcoded return value is the most 
version specific binary.  I.e.

static char *progname = python2.7;

--
components: Interpreter Core
messages: 125420
nosy: allan
priority: normal
severity: normal
status: open
title: sys.executable default and altinstall
versions: Python 2.5, Python 2.6, Python 2.7, Python 3.1, Python 3.2, Python 3.3

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[R. David Murray]

R. David Murray rdmur...@bitdance.com added the comment:

Another alternative might be to return None (refuse the temptation to 
guess).  But, given the long standing nature of the current guessing, having 
it return the specific version string may indeed make sense.

--
keywords: +easy
nosy: +r.david.murray
stage:  - unit test needed
type:  - behavior
versions:  -Python 2.5, Python 2.6, Python 3.3

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[R. David Murray]

Changes by R. David Murray rdmur...@bitdance.com:


--
nosy: +ncoghlan

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[Antoine Pitrou]

Changes by Antoine Pitrou pit...@free.fr:


--
nosy: +barry

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[Barry A. Warsaw]

Barry A. Warsaw ba...@python.org added the comment:

For Python  3.2, I think adding the version number alone makes sense.  Can you 
think of any situations where the trailing digits could break something?

For Python 3.2 I'd suggest also adding the build flags to sys.executable.  If 
you want the most specific binary, that would make the most sense.

--

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[R. David Murray]

R. David Murray rdmur...@bitdance.com added the comment:

Well, the digits are there if they are there in the name when that's actually 
what is in argv[0], so as long as that's the name the binary is actually 
installed under I don't think it will break anything.  I presume the same 
applies to the abi flags but haven't checked.

That said, I don't know for sure that progname is the right thing to change; I 
haven't looked through the code to see how sys.executable is generated or if 
there is anything else GetPythonName is used for.

Hmm.  I suppose there could be an issue if Python is invoked through a 
wrapper...I know Gentoo does that, so I've added Arfrever to nosy to see if he 
has an opinion.

--
nosy: +Arfrever

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue10835] sys.executable default and altinstall

[Arfrever Frehtes Taifersar Arahesis]

Arfrever Frehtes Taifersar Arahesis arfrever@gmail.com added the comment:

I rather doubt that there will be any problem with Python invoked through a 
wrapper.
Gentoo's python-wrapper isn't used when target executable (e.g. 
/usr/bin/python3.1) is directly called.  A side effect of python-wrapper is 
that sys.executable is the target executable:
$ readlink /usr/bin/python
python-wrapper
$ /usr/bin/python -c 'import sys; print(sys.executable)'
/usr/bin/python3.1
$ /usr/bin/python-wrapper -c 'import sys; print(sys.executable)'
/usr/bin/python3.1
$ sh -c exec -a '' /usr/bin/python -c 'import sys; print(sys.executable)'
/usr/bin/python3.1
$ sh -c exec -a '' /usr/bin/python3.1 -c 'import sys; print(sys.executable)'
/usr/bin/python

If there is a patch, then I can test it.

--

___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue10835
___
___
Python-bugs-list mailing list
Unsubscribe: 
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com