Re: Testing if there is data on stdin?

[Lloyd Zusman <ljz@xxxxxxxxxx>]

Atom Smasher <atom@xxxxxxxxxxx> writes:

> 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.

Thanks for all of this in both of your messages. This is very clear and
it's a great help.


-- 
 Lloyd Zusman
 ljz@xxxxxxxxxx
 God bless you.