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From: Chimu on 13 Mar 2010 09:21
On Mar 13, 7:09 pm, Ben Bacarisse <ben.use...(a)bsb.me.uk> wrote:
> Chimu <ech...(a)gmail.com> writes:
> > I got data in $x separated by :, further each field has 4 values and i
> > want get those. So i come with IFS and read code
> > Input
> > x="tab1,c,1,3,db1:tab2,d,21,13,db45:tab12,t,11,16,db4"
>
> > output
> > Data feed: tab1 c 1 3 db1
> > Data feed: tab2 d 21 13  db45
> > Data feed: ab12 t 11 16 db4
>
> > my code so far
> > ~~~~~~~~~~
> > while IFS=: read -r field
> > do
> >    while IFS=, read -r a b c d
> >    do
> >            echo "Data feed: $a $b $c $d"
> >    done <<<"$field"
> >        #IFS=:
> > done <<<$x
> > ~~~~~~~~~~
>
> > so far it is not working and i'm not able to pull data. i don't wanna
> > use external tool just bash builtin and IFS. any thoughts on how to
> > fix this? are you allowed to use multiple IFS? btw, I'm using bash 3.x
> > on Debian Linux server.
>
> read will read a line and you have only one line of input so there is
> nothing to loop over in the outer loop.  The other problem you are
> seeing is that 'field' and 'd' both get set to the remaining words and
> separators which is not what you want.  Also, the inner loop is not
> really serving any purpose.
>
> There a lots of ways to do this, but the one that is closest to your
> original is probably:
>
>   echo "$x:" | while read -r -d: field
>   do
>       IFS=, read -r a b c d rest <<<"$field"
>       echo "Data feed: $a $b $c $d"
>   done
>
> The -d flag causes the while/read loop to see multiple "lines".  The
> echo adds a terminating separator so that the last "line" is seen.
> The rest variable in the inner read collects anything left over after
> the parts you want.
>
> --
> Ben.
Wow.

I actually come with something, but your solution seems nice too and
it never use to IFS. Here is what I did
--
IFS=: read -r field <<<$x
for f in $field
do
IFS=, read -r a b c d <<<"$f"
echo "Data feed: $a $b $c $d"
done
--
Guess i need to read "bash read builtin" man page as I wasn't aware of
-d switch. May I know why you prefixed : for $x ?

Thanks a lot for quick response.
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