Re: Testing if there is data on stdin?

[Atom Smasher <atom@xxxxxxxxxxx>]

On Thu, 17 Sep 2009, Lloyd Zusman wrote:

> The reason I want to do this is because I have a zsh script which, under 
> certain circumstances, needs to get its arguments via stdin instead of 
> from the command line. I'd like to be able to test within the script 
> whether there is data waiting on stdin, and if so, to read it and use it 
> to construct the argument list. If there is no data waiting on stdin, 
> then I just want to get the arguments from the command line.
======================

  read -t foo || { print -n "Input required from TTY: " ; read foo }
  echo ${foo}


> Also, there is a slight difference in processing logic if I find data in 
> stdin, and I need to do a little bit of special initialization _before_ 
> I try to read that data ... but only if that data is on stdin waiting to 
> be read.
=================

  if { read -t foo } {
      ## do this if input was read from STDIN
      print "Input read from stdin: ${foo}"
  } else {
      ## do this if input comes from TTY
      print -n "Input required from TTY: "
      read foo
      print "Input read from TTY: ${foo}"
  }


if the input you're looking for is on a single line you shouldn't have to 
mess with zselect.


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