From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailsrv.cs.umass.edu (mailsrv.cs.umass.edu [128.119.240.136]) by sourceware.org (Postfix) with ESMTPS id A50203851C36 for ; Sat, 5 Sep 2020 17:11:26 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org A50203851C36 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=cs.umass.edu Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=moss@cs.umass.edu Received: from [192.168.0.30] (c-24-62-203-86.hsd1.ma.comcast.net [24.62.203.86]) by mailsrv.cs.umass.edu (Postfix) with ESMTPSA id 3D696401F174; Sat, 5 Sep 2020 13:11:26 -0400 (EDT) Reply-To: moss@cs.umass.edu Subject: Re: Is this a bug in bash? To: Greg Borbonus Cc: Bob McGowan , The Cygwin Mailing List References: <50fad2a4-22c3-8de8-3a0a-394c0b95048b@gmail.com> <824c5748-594e-cf7c-4bba-4b70f9f593b1@cs.umass.edu> From: Eliot Moss Message-ID: <4d932cce-4c25-1458-453b-87d02bb38a03@cs.umass.edu> Date: Sat, 5 Sep 2020 13:11:26 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-3.9 required=5.0 tests=BAYES_00, JMQ_SPF_NEUTRAL, KAM_DMARC_STATUS, NICE_REPLY_A, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: cygwin@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Cygwin discussions and problem reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 05 Sep 2020 17:11:28 -0000 On 9/5/2020 12:57 PM, Greg Borbonus wrote: > Yeah, thought the expansion might be causing the issue. > > Thanks, > Greg Borbonus > > On Sat, Sep 5, 2020, 10:44 AM Eliot Moss > wrote: > > On 9/5/2020 11:29 AM, Greg Borbonus via Cygwin wrote: >  > Out of curiosity, why are there 2 different sets of quotes? >  > >  > Thanks, >  > Greg Borbonus >  > >  > On Fri, Sep 4, 2020, 10:23 PM Bob McGowan via Cygwin > >  > wrote: >  > >  >> I am trying to set things up so the Bash profile detects if bash is >  >> running from the Windows "XWin Server" startup link or not. The startup >  >> link has the following as the command: >  >> >  >> C:\cygwin64\bin\run.exe --quote /usr/bin/bash.exe -l -c "cd; exec >  >> /usr/bin/startxwin" >  >> >  >> So I thought I'd try adding the env command to set an environment variable: >  >> >  >> C:\cygwin64\bin\run.exe --quote /usr/bin/env startxwin=yes >  >> /usr/bin/bash.exe -l -c "cd; exec /usr/bin/startxwin" >  >> >  >> This works (if there's a better way, I'd be happy to learn of it) but in >  >> the process of testing I had a problem when echo'ing the variable. >  >> >  >> For purposes of describing the bug, I simplified the command as follows: >  >> >  >>       env startup=yes bash -l -c 'echo "cmd:  $startup"' >  >> >  >> I also added an "echo profile: $startup" to the .bash_profile file. >  >> >  >> When I run the above in a Cygwin shell, the output is: >  >> >  >> $ env startup=yes bash -l -c "echo cmd: $startup" >  >> profile: yes >  >> $ >  >> >  >> When I run it in a Linux shell, the output is: >  >> >  >> $ env startup=yes bash -l -c 'echo "cmd:  $startup"' >  >> profile: yes >  >> cmd:  yes >  >> $ >  >> >  >> As you can see, the Cygwin side fails to generate any output from the -c >  >> echo command but on the Linux system there is output. >  >> >  >> Normally I'd call this a bug but since this is running under Windows it >  >> may be some weirdness of the implementation required to create the Linux >  >> like environment. >  >> >  >> The Bash version in Cygwin is  4.4.12(3)-release and for my Debian Linux >  >> system, it is 5.0.3(1)-release.  So it could also be that it existed in >  >> Linux 4.x series and has been fixed in the 5.x series. > > The inner quotes are necessary because there are two spaces beween cmd: and > $startup, and the : may be risky unquoted in bash (actually it is ok, but I > try to be careful about anything not a letter or digit, etc.).  The outer ones > are single quotes, which protect $startup from being expanded before it gets > to the new bash.  " " (double) quotes do not prevent $ expansion.  (You want > the new bash to do the expansion.)  However, I think this would also work: > >      env startup=yes bash -l -c echo 'cmd:  $startup' Please put responses at the bottom ("Don't top post") on this list. I wasn't saying the quotes were a problem, only explaining to a correspondent why they might be necessary, etc. EM