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Re: Challenge: a VERY strange problem with command substitution in bash
- From: Wouter van Doorn <wouter at vandoorn dot tv>
- To: Richard Beels <rbeels at yahoo dot com>, cygwin at cygwin dot com
- Date: Wed, 12 Jul 2017 07:06:51 +0100
- Subject: Re: Challenge: a VERY strange problem with command substitution in bash
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- References: <email@example.com> <59655e58.d532240a.ae3d8.4253SMTPIN_ADDED_MISSING@mx.google.com>
I bet Comodo is the golden tip. They have introduced whitelisting
without telling anyone, and I have had very strange behaviour (strange
until that whitelist explained it) too. Including that subshell thing.
They call it 'auto-containment'. Just disable that, and done.
On 12 July 2017 at 00:22, Richard Beels via cygwin <firstname.lastname@example.org> wrote:
> At 07/11/2017 at 15:12, Shakespearean monkeys danced on JÃ¼rgen Wagner's
> keyboard and said:
>> Using backquotes instead of the command substitution with $(...) does not
>> change the results. I could swear this did work in an earlier version of
>> Cygwin on my Windows 7 machine.
>> I tried this to see if the code in the parentheses is executed at all:
>> $ value="$( date 2> foo | cat )"; echo "$? <$value>"
>> The file "foo" was not created, i.e., it seems the commands don't really
>> get executed.
>> $ value="$( date && pwd )"; echo "$? <$value>"
>> 0 <Tue Jul 11 20:49:09 CEST 2017
>> $ value="$( date || pwd )"; echo "$? <$value>"
>> 0 <Tue Jul 11 20:32:27 CEST 2017>
>> both work, so some control structures seem to be permissible... just not a
>> What is going on? Some misconfiguration? A Cygwin bug? Some interaction
>> with something weird in Windows 10? I am at loss to understand what could be
>> wrong... and am now most curious whether anybody has an idea what is causing
>> this. Does it work/not work in the same way in your Cygwin installation?
>> I came across this effect because ssh-host-config did not recognize me as
>> administrator anymore. It's due to a check for a certain user group that
>> uses a command substitution with a pipe. Replacing this with an equivalent
>> command works. The original line used "id -G" and then a "grep -Eq" to check
>> whether a certain group is on that list.
>> I am VERY curious now! I've rarely been puzzled that much by such a very
>> elementary shell expression (looking back at 34 years of Unix experience).
> Hi Jurgen.
> 90% chance it's what is called bloda in these parts. It's in the FAQ on
> cygwin.com. I'll go out on a limb and say you might have just
> installed/changed your AV/Firewall software.
> And if I want to be super-psychic, can I guess comodo? Because I just
> changed to comodo a couple weeks ago and had the same subshell/command
> substitution/pipeline errors you're mentioning.
> If so, you need to exclude your cygwin folder from AV scanning. AND... if
> the software does whitelisting or host intrusion protection (HIPS) or "run
> unknown executables in a container/sandbox" or something similar, you also
> need to trust all the executables, too. Or switch to something else that
> doesn't trip cygwin's trigger.
> After doing that and a rebaseall, I haven't had a fork error in a week. I
> can't wait to run setup and come up with an update process, though...
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