Re: What is the source of my input, file or STDIN?

[drieux]

On Jan 6, 2004, at 1:07 PM, david wrote:
[EMAIL PROTECTED] wrote:
Case 3. (this is the difficult case for me) the script is invoked
with no file and no pipe to it.  I would like the script to
end quietly, such as
test.input.source

Instead, it waits for input.

test.input.source
no command line args - switching to STDIN

and now it waits forever.
select / IO::Select is what you are looking for.
[..]

My compliments to David, as always.

The reason the code is 'waiting for ever' in
the case of having no STDIN is that it is in a
blocking IO Read on STDIN.
So since we have a better spec, I have updated the code
to show how the IO::Select could be used to gate
for the case that the code was called without
command line input, nor a current connection for STDIN.
<http://www.wetware.com/drieux/pbl/perlTrick/CommandLine/ 
file_or_stdin.plx>

Note all of the noisy 'print statements' are there
merely to show the transition of the logic of the code.
On Jan 6, 2004, at 12:53 PM, Steve Grazzini wrote:

On Jan 6, 2004, at 3:17 PM, [EMAIL PROTECTED] wrote:
Case 3. (this is the difficult case for me) the script is
invoked with no file and no pipe to it.  I would like the
script to end quietly
  die usage() if @ARGV == 0 and -t;
You might not want to test if there is a
controlling terminal - since that would prevent
the pipe fitting from working unless there was a
controlling terminal. A problem that will crop up
when JoeBob opts wants to use the pipe fitting in
their KSH script...
I didn't show you how to check for the pipe (-p) because
this should probably work, too:
  % your-script <input.txt
We have Sooooo got to talk about your meds here...

8-)

To be honest, I had not thought about the idea of
'-p' even trying to test to see if it was a pipe
since it is-ish when one connects the pipe fittings
of the standard shell, or as you have done, the
express redirection of input...
[jeeves: 30:] wc -l funk*
      14 funk_env.plx
[jeeves: 31:] ./file* < funk*
no command line args - switching to STDIN
STDIN had 14 number of lines
we saw 14 number of lines
[jeeves: 32:]
The 'redirect in' of "<" simply is a way of changing
how STDIN is feed to the calling program by the shell.
It of course is dependent upon how the shell copes
with re-attaching STDIN|STDOUT combo's...
ciao
drieux
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