I'm new to scripting, and I'm attempting to write a script in ksh that
uses named pipes. My pseudo-code is:

mkfifo $DATA
startReader &
sleep 10 # let reader finish initialization
startWriter

function startReader
{
request_for_database << !@!
1. perform some initialization on database
tables
2. start sucking on named pipe $DATA # blocks
here waiting for Writer
!@!
}

function startWriter
{
<write to named pipe $DATA>
}

So my goal is:
* Reader performs setup on database tables
* Reader starts sucking on pipe
* After 10 seconds, Writer starts writing to pipe

This seems to work fine for the most part - but occasionally the
Reader's initialization code fails. In this case, I need to abort the
entire process.
When the initialization fails:
* Reader process immediately dies, before writer starts
* Writer blocks waiting for someone to open the pipe for
reading

At this point I have to kill everyting manually. Is there any code I
can put in either the writer or reader that will the situation?
What I really want is for the writer to test for the presence of a
reader, then abort if no process is listening (b/c iniialization
failed) instead of hang. But nothing I've tried does exactly that. If
there's a better idea, I'm open to that too.

Thanks in advance.

anon wrote:
> I'm new to scripting, and I'm attempting to write a script in ksh that
> uses named pipes. My pseudo-code is:

> request_for_database << !@!
> # 1. perform some initialization on database tables
> # 2. start sucking on named pipe $DATA

Databases are kind of a special case, and solutions are
usually dependent on which are being used. For Oracle
(for instance), see:

http://rootshell.be/~yong321/compute...leAndPerl.html

Also investigate the perl:BI module. I know it's not ksh(1)
and more than you desire to know, but the code is robust
and practical.

For documents and examples for k/sh(1), see:

"Shell Corner: Use Named Pipes in the Shell"
http://www.unixreview.com/documents/...1031588957510/

(including the script examples listed after the article.)

"qpipe.ksh"
http://www.sun.com/bigadmin/scripts/...ipts/qpipe.txt

=Brian