Re: Piping output from sqlplus

[Christopher Faylor <cgf-no-personal-reply-please at cygwin dot com>]

On Thu, Dec 16, 2004 at 03:29:16PM -0500, Chuck wrote:
>I'm having a strange problem reading the output from sqlplus in Cygwin.
>Sqlplus is a windows command line program used to access oracle
>databases. My command looks something like this...
>
>sqlplus -s <<! | read line
>user/password@database
>set pagesize 0 linesize 200 feedback off tab off
>select col1||chr(9)||col2
>from table;
>!
>
>This should output one line to stdout with the two values separated by a
>tab character. The read command should read it into the variable $line.
>On my Solaris system it works perfectly. In Cygwin, $line is empty.

Just to demonstrate what you're seeing without the sqlplus requirement:

  bash$ echo hello | read line
  bash$ echo $line

  bash$

The reason for the behavior is apparently that when you use read in a
pipe like this bash and ash fork a separate process so the variable only
exists very briefly in that process and `line' is never defined in the
main process.

zsh does what you'd expect, so if you can use zsh instead of bash, that
would be a solution.  Otherwise, you probably will have to experiment
with setting IFS and using either $(sqlplus) or `sqlplus` .

cgf

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