From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 105537 invoked by alias); 5 Dec 2018 06:55:16 -0000 Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Received: (qmail 105506 invoked by uid 89); 5 Dec 2018 06:55:15 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-5.7 required=5.0 tests=BAYES_05,GIT_PATCH_2,KAM_NUMSUBJECT,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy=cygwincom, cygwin.com, UD:cygwin.com, eboyd53 X-HELO: lb2-smtp-cloud7.xs4all.net Received: from lb2-smtp-cloud7.xs4all.net (HELO lb2-smtp-cloud7.xs4all.net) (194.109.24.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 05 Dec 2018 06:55:12 +0000 Received: from tmp.UTSNUI6EfU ([83.162.234.136]) by smtp-cloud7.xs4all.net with ESMTPSA id UR5OgyJFuaOW5UR5QgIhDw; Wed, 05 Dec 2018 07:55:08 +0100 Date: Wed, 05 Dec 2018 06:55:00 -0000 Message-ID: From: Houder Reply-To: cygwin@cygwin.com To: cygwin@cygwin.com Subject: Re: Bash heredoc on FD 3 References: <5c0427c5.1c69fb81.d71e5.c8ec@mx.google.com> In-Reply-to: Content-Type: text/plain; charset=UTF-8; format=fixed User-Agent: mua.awk 0.99 X-SW-Source: 2018-12/txt/msg00047.txt.bz2 On Tue, 4 Dec 2018 09:21:55, cyg Simple wrote: > Dash is faster in processing the data but can be made to fail if you > add -d to the ls commands you're using. ? Oh, I believe you refer to: https://cygwin.com/ml/cygwin/2018-12/msg00035.html ( Re: Bash heredoc on FD 3 ) > So in Bash the process is no longer available. Adding -d to the above: > > $ dash -c '/bin/ls -ld /dev/fd/*' > /bin/ls: cannot access '/dev/fd/3': No such file or directory > lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec 3 10:50 /dev/fd/0 -> /dev/pty2 > lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec 3 10:50 /dev/fd/1 -> /dev/pty2 > lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec 3 10:50 /dev/fd/2 -> /dev/pty2 uhm, the facts are slightly different ... /dev/fd is, well, a "moving target", it is symlnk to /proc/self/fd. self refers to the "current process" ... it changes each time. /proc/self/fd shows the open fd's of the current process ... Currently, I am on Linux (Fedora) ... @@ # currently I am executing the shell (bash) @@ # self points to the procid of my bash ... @@ printf "%s\n" /dev/fd/* /dev/fd/0 /dev/fd/1 /dev/fd/10 /dev/fd/11 /dev/fd/2 /dev/fd/255 /dev/fd/3 @@ # however ls has NO open fd 3 if I invoke it like this: @@ # (self points to the procid of my ls command) @@ ls -ld /dev/fd/* # /dev/fd/* expands to the list above (bash) ls: cannot access '/dev/fd/255': No such file or directory ls: cannot access '/dev/fd/3': No such file or directory lrwx------ 1 henri henri 64 Dec 5 07:26 /dev/fd/0 -> /dev/pts/0 lrwx------ 1 henri henri 64 Dec 5 07:26 /dev/fd/1 -> /dev/pts/0 lrwx------ 1 henri henri 64 Dec 5 07:26 /dev/fd/10 -> /dev/dri/card0 lrwx------ 1 henri henri 64 Dec 5 07:26 /dev/fd/11 -> /dev/dri/card0 lrwx------ 1 henri henri 64 Dec 5 07:26 /dev/fd/2 -> /dev/pts/0 @@ # ls HAS an open fd 3 if I invoke it like this: @@ (# use strace to see it happen -- ls opens the directory) @@ ls -lL /dev/fd # /dev/fd refers to /proc/self/fd total 0 crw------- 1 henri tty 136, 0 Dec 5 07:38 0 crw------- 1 henri tty 136, 0 Dec 5 07:38 1 crw-rw----+ 1 root video 226, 0 Dec 5 07:01 10 crw-rw----+ 1 root video 226, 0 Dec 5 07:01 11 crw------- 1 henri tty 136, 0 Dec 5 07:38 2 dr-x------ 2 henri henri 0 Dec 5 07:38 3 @@ ls -l /proc/self/fd total 0 lrwx------ 1 henri henri 64 Dec 5 07:38 0 -> /dev/pts/0 lrwx------ 1 henri henri 64 Dec 5 07:38 1 -> /dev/pts/0 lrwx------ 1 henri henri 64 Dec 5 07:38 10 -> /dev/dri/card0 lrwx------ 1 henri henri 64 Dec 5 07:38 11 -> /dev/dri/card0 lrwx------ 1 henri henri 64 Dec 5 07:38 2 -> /dev/pts/0 lr-x------ 1 henri henri 64 Dec 5 07:38 3 -> /proc/2605/fd Same w/ dash: @@ dash $ printf "%s\n" /dev/fd/* /dev/fd/0 /dev/fd/1 /dev/fd/10 /dev/fd/11 /dev/fd/12 /dev/fd/17 /dev/fd/18 /dev/fd/2 /dev/fd/3 /dev/fd/55 $ ls -ld /dev/fd/* ls: cannot access '/dev/fd/12': No such file or directory ls: cannot access '/dev/fd/3': No such file or directory lrwx------ 1 henri henri 64 Dec 5 07:25 /dev/fd/0 -> /dev/pts/3 lrwx------ 1 henri henri 64 Dec 5 07:25 /dev/fd/1 -> /dev/pts/3 lrwx------ 1 henri henri 64 Dec 5 07:25 /dev/fd/10 -> /dev/dri/card0 lrwx------ 1 henri henri 64 Dec 5 07:25 /dev/fd/11 -> /dev/dri/card0 lrwx------ 1 henri henri 64 Dec 5 07:25 /dev/fd/17 -> /dev/dri/card0 lrwx------ 1 henri henri 64 Dec 5 07:25 /dev/fd/18 -> /dev/dri/card0 lrwx------ 1 henri henri 64 Dec 5 07:25 /dev/fd/2 -> /dev/pts/3 lr-x------ 1 henri henri 64 Dec 5 07:25 /dev/fd/55 -> /home/b/henri/.local/share/baloo/index ===== -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple