From: Joachim Wuttke <j.wuttke@...>
Date: 2011-03-07T17:55:02+09:00
Subject: [ruby-core:35446] [Ruby 1.9 - Bug #4477][Open] Kernel:exec and backtick (`) don't work for certain system commands


Issue #4477 has been reported by Joachim Wuttke.

----------------------------------------
Bug #4477: Kernel:exec and backtick (`) don't work for certain system commands
http://redmine.ruby-lang.org/issues/4477

Author: Joachim Wuttke
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: 1.8.7 and 1.9.0


From documentation and common sense, I would expect that Kernel:exec and backtick (`) work for _all_ kind of system commands. This is currently not the case.

~$ cat test1
echo success
~$ cat test2
#!/bin/sh
echo success
~$ chmod a+x test?
~$ ruby1.8 -e 'p `test1`'
-e:1: command not found: test1
""
~$ ruby1.9 -e 'p `test1`'
-e:1:in ``': Exec format error - test1 (Errno::ENOEXEC)
        from -e:1:in `<main>'
~$ ruby1.8 -e 'p `test2`'
"success\n"
~$ ruby1.9 -e 'p `test2`'
"success\n"

This problem has been reported before (#3856: strange Kernel#exec behavior with bash's source command). As a workaround, it has been suggested to append a semikolon to the system command:

~$ ruby1.8 -e 'p `test1;`'
"success\n"
~$ ruby1.9 -e 'p `test1;`'
"success\n"

The report #3856 has been closed with the decision "not a bug".

This I cannot accept. For many years, I got used to run system commands through `<cmd>`. When it failed, I spent painfully long time to search for a bug in my Ruby code and in the system command before I realized the problem was due to an unexpected restriction of Ruby's exec/backtick.


-- 
http://redmine.ruby-lang.org