gawk treats pipe FS-delimiters inconsistently

Hi there

I'm using gawk 3.1.6 to parse some output from isql (Sybase) that looks
like the following:

|data_type|type_name       |precision  |length     |scale |
|---------|----------------|-----------|-----------|------|
|        4|int             |         10|          4|     0|
|        1|char            |          7|          7|  NULL|
|       12|varchar         |         50|         50|  NULL|
|       12|varchar         |         35|         35|  NULL|
|       12|varchar         |         35|         35|  NULL|
|       12|varchar         |         35|         35|  NULL|
|       12|varchar         |         35|         35|  NULL|
|       12|varchar         |         15|         15|  NULL|
|       12|varchar         |         25|         25|  NULL|
|        1|char            |          2|          2|  NULL|
|       12|varchar         |         30|         30|  NULL|
|        1|char            |          1|          1|  NULL|

To do so, I am using a regexp FS as follows:

BEGIN { FS=" *| *";     OFS = "\t" }
{ 
    print $1, $2, $3, $4, $5    
}

The result is that the fields are indeed split on the pipes, but field values
all INCLUDE the pipes as well! Whereas if the pipes are say colons, and i use
FS=" : ", then i get expected results .. viz: the colons are NOT included
with the field values.

I have tried escaping the pipe (|) .. but gawk reports that it is not
necessary to do so:

awk: awk\readpipes.awk:7: warning: escape sequence \|' treated as plain|'

Am i doing something wrong, or is this a bug/problem that i need to find a
workaround for?

TIA

no that is not a bug. you have to escape twice like this

FS=" *\\| *";

for more information read this

http://www.gnu.org/software/gawk/manual/gawk.html#Computed-
Regexps

Yes, you're doing something wrong. The pipe symbol '|' is the regex
alternation operator so you are telling gawk that the field separator is
either 'a bunch of blanks' or 'a bunch of blanks'; so gawk does exactly what
you ask it to do.

Try FS=" * *" and you should see a difference-- is used to create a character
list. However, based on how your data is structured and the regex FS
seperator, field $1 will be null so your code won't print the column with
NULLs in it. You probably want to use print $2, $3, $4, $5, $6.

HTH

Awesome - Thank you both for two excellent answers!

It's good to know the right way (raysatiro), but i love the lateral solution
too (lowella).

Thanks again!

=oD