MULTIOS input

MULTIOS input

[Dave Yost]

Is this working correctly?  I'm on Mac OS X 10.4.10.

0 298 Z% cat foo
#!/usr/local/packages/zsh/bin/zsh

echo ZSH_VERSION is $ZSH_VERSION

setopt MULTIOS

echo line 2 \
| (
cat <<< 'line 1
' < /dev/fd/0
)
0 299 Z% ./foo
ZSH_VERSION is 4.3.4
line 1

0 300 Z%

Re: MULTIOS input

[Bart Schaefer]

On Jun 27, 12:40pm, Dave Yost wrote:
}
} Is this working correctly?  I'm on Mac OS X 10.4.10.

It's not working incorrectly, I guess.

I'm not sure if this is part of your question, but the <<< operator
appends an implicit newline, so the newline you embedded in the
quotes makes two.

/dev/fd/0 refers to the standard input, which is NOT the standard input
of the subshell (the pipe from "echo line 2") -- it's the standard
input of "cat", which (when I try it on linux) is the <<< operator, so
I see "line 1\n\n" twice.

Whether that's what you get on some other OS depends on whether there
really is a /dev/fd/0 or whether zsh is simulating it, and possibly on
whether the I/O buffering is such that you can read the same input from
the /dev/fd device more than once.

 
} 0 298 Z% cat foo
} #!/usr/local/packages/zsh/bin/zsh
} 
} echo ZSH_VERSION is $ZSH_VERSION
} 
} setopt MULTIOS
} 
} echo line 2 \
} | (
} cat <<< 'line 1
} ' < /dev/fd/0
} )
} 0 299 Z% ./foo
} ZSH_VERSION is 4.3.4
} line 1
} 
} 0 300 Z%
}-- End of excerpt from Dave Yost

Re: MULTIOS input

[Wayne Davison]

On Wed, Jun 27, 2007 at 12:40:33PM -0700, Dave Yost wrote:
> #!/usr/local/packages/zsh/bin/zsh
> echo ZSH_VERSION is $ZSH_VERSION
> setopt MULTIOS
> echo line 2 \
> | (
> cat <<< 'line 1
> ' < /dev/fd/0
> )

This works for me under Linux:

setopt MULTIOS
echo line 2 | (
cat 9<&0 <<< 'line 1' <&9
)

That dups the current fd0 (the pipe) to fd9, and then takes the input
from fd9 after the <<< data.

..wayne..

Re: MULTIOS input

[Bart Schaefer]

On Jun 29, 11:34am, Wayne Davison wrote:
}
} This works for me under Linux:
} 
} setopt MULTIOS
} echo line 2 | (
} cat 9<&0 <<< 'line 1' <&9
} )

This works, too:

echo line 2 | ( cat <<< 'line 1' <<(</dev/fd/0) )

The trick is to force /dev/fd/0 to be opened before <<< changes stdin.
In fact you don't even need to fork the subshell, just use braces:

echo line 2 | { cat <<< 'line 1' <<(</dev/fd/0) }