#8474: Detect whether a program is in the path
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Reporter: jhpalmieri | Owner: drkirkby
Type: defect | Status: needs_review
Priority: blocker | Milestone: sage-4.3.4
Component: porting | Keywords:
Author: John Palmieri | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by jhpalmieri):
Just to emphasize: on t2.math, I get this behavior (in contrast to using
"command -v" or "type"):
{{{
sage: from subprocess import call, PIPE
sage: call('which ' + 'ls', shell=True, stdout=PIPE, stderr=PIPE)
0
sage: call('which ' + 'lljsdfs', shell=True, stdout=PIPE, stderr=PIPE)
0
}}}
I don't know why. The same happens with {{{os.system('which lljsdfs')}}},
and this is what is used in the Sage library. ("call" is similar in
behavior to "os.system", but I think "call" is slightly preferred. It
also gives better control of stdin, stdout, and stderr.) So I do think
this is what's wrong with #8463. As I said in the description of this
ticket, the function "have_latex" returns True on t2.math, and I would
guess that if I could install Sage 4.3.4.alpha0 on t2.math, then the
comparable "have_chomp" functions would return True as well. Therefore
Sage would try to call chomp when doing homology calculations, and since
the program isn't there, it would crash.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8474#comment:5>
Sage <http://www.sagemath.org>
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