Re: Bash heredoc on FD 3

[cyg Simple <cygsimple at gmail dot com>]

On 12/3/2018 10:43 AM, cyg Simple wrote:
> On 12/2/2018 1:43 PM, Steven Penny wrote:
> > Using this file:
> >
> >     $ cat hello.sh
> >     awk -f /dev/fd/3 3<<eof
> >     BEGIN {
> >       print "hello world"
> >     }
> >     eof
> >
> > it runs as expected with Dash:
> >
> >     $ dash hello.sh
> >     hello world
> >
> > However it fails with Bash:
> >
> >     $ bash hello.sh
> >     awk: fatal: can't open source file `/dev/fd/3' for reading (No 
> > such file or
> >     directory)
> >
> > I tried also with Debian and both Dash and Bash work as expected. What is
> > causing Cygwin Bash to fail here?
>
> Same for me and interestingly:
>
> $ ls -ld /dev/fd/*
> ls: cannot access '/dev/fd/3': No such file or directory
> ls: cannot access '/dev/fd/31': No such file or directory
> lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec  3 10:39 /dev/fd/0 -> /dev/pty2
> lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec  3 10:39 /dev/fd/1 -> /dev/pty2
> lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec  3 10:39 /dev/fd/2 -> /dev/pty2

And:

$ dash -c '/bin/ls -l /dev/fd/'
total 0
lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec  3 10:51 0 -> /dev/pty2
lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec  3 10:51 1 -> /dev/pty2
lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec  3 10:51 2 -> /dev/pty2
lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec  3 10:51 3 -> /proc/27356/fd

$ dash -c '/bin/ls -l /dev/fd/'
total 0
lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec  3 10:51 0 -> /dev/pty2
lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec  3 10:51 1 -> /dev/pty2
lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec  3 10:51 2 -> /dev/pty2
lrwxrwxrwx 1 eboyd53 eboyd53 0 Dec  3 10:51 3 -> /proc/18740/fd


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


--
cyg Simple

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