Date: Sun, 12 Jun 2005 22:34:23 -0500 From: Mike Meyer <mwm@mired.org> To: Dan Nelson <dnelson@allantgroup.com> Cc: Christopher Black <cblack@securecrossing.com>, questions@freebsd.org Subject: Re: Problems with command line scratch files in zsh Message-ID: <17068.65215.389984.290550@guru.mired.org> In-Reply-To: <20050613020118.GB20259@dan.emsphone.com> References: <17067.62149.92183.56827@guru.mired.org> <1118608948.705.6.camel@localhost> <17068.51586.885638.130044@guru.mired.org> <20050613020118.GB20259@dan.emsphone.com>
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In <20050613020118.GB20259@dan.emsphone.com>, Dan Nelson <dnelson@allantgroup.com> typed: > In the last episode (Jun 12), Mike Meyer said: > > [Format recovered from top posting.] > > In <1118608948.705.6.camel@localhost>, Christopher Black <cblack@securecrossing.com> typed: > > > On Sun, 2005-06-12 at 03:31 -0500, Mike Meyer wrote: > > > > Since going to 5.x with devfd, I've noticed that some of the > > > > shell constructs used by zsh (and other shells - I know zsh > > > > didn't invent this) quit working. To wit: > > > > > > > > guru% wc <(cat /etc/motd) > > > > wc: /dev/fd/11: open: No such file or directory > > > > > > > > The <(...) construct runs the pipe in (), and replaces the <(...) > > > > with the name of the /dev/fd/ entry for the output of that pipe. > > > > The file exists for the shell process doing all this. But when > > > > the comm process tries to open the file to read the data, the > > > > file doesn't exist. This is pretty nasty. > > > > > > > > Anyone got any suggestions on how to fix this? A bug report with > > > > a patch, maybe (I couldn't find any such bug report)? > > > > Workarounds? Maybe this should go to hackers@freebsd.org? > > > Why not just 'cat /etc/motd | wc' ? > > > > Because I used a trivial example designed to illustrate the problem. A > > less trivial example would be: > > > > comm -12 <(sort file_one) <(sort file_two) > > > > Of course, this can also be rewritten using temp files instead of > > pipes. But that will be longer, slower, and uglier. > > > > This worked on 4.X. It ought to work on 5.X. > > If you want a tempfile, you should probably use the =() syntax, which > will always use a tempfile. <() and >() will attempt to use /dev/fd. > It probably worked on 4.* because 4.* creates 64 /dev/fd/* device nodes > on install. If for some reason zsh had more than 64 files open > already, it would have failed even on 4.*. But I don't want temp files, I want pipes. That's why I used <(). <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/consulting.html Independent Network/Unix/Perforce consultant, email for more information.
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