On Mon, 24 Mar 2008 10:08:24 -0700, aixdude@yahoo.com wrote:

> only want to report first line, each time PNAM= value changes second
> field delimited by | character sample of source file
>
> STAR=20080317 20:43:59|PNAM=ABSPC103
> STAR=20080318 20:42:53|PNAM=ABSPC103
> STAR=20080319 20:43:27|PNAM=ABSPC103
> STAR=20080320 20:43:00|PNAM=ABSPC103
> STAR=20080321 20:41:41|PNAM=ABSPC103
> STAR=20080301 01:41:49|PNAM=ACFPC360
> STAR=20080302 02:35:03|PNAM=ACFPC360
> STAR=20080303 01:10:23|PNAM=ACFPC360
> STAR=20080319 03:56:12|PNAM=EDIPP757
> STAR=20080320 03:54:41|PNAM=EDIPP757
> STAR=20080321 03:55:14|PNAM=EDIPP757
> STAR=20080322 03:53:57|PNAM=EDIPP757
> STAR=20080301 12:02:48|PNAM=HHRAC010
> STAR=20080301 18:02:48|PNAM=HHRAC010
> STAR=20080303 12:04:33|PNAM=HHRAC010
>
> etc

(untested)

awk -F\| '$2 != x { print $0; x=$2 ; }'