Since you're doing character processing rather than record processing,
isn't C your best tool for the job here?
This is what I whipped out YMMV:
#include <u.h>
#include <libc.h>
#include <bio.h>
char *str;
int ntok;
#define WHITESPACE(c) ((c) == ' ' || (c) == '\t' || (c) == '\n')
void
chgtok(Biobuf *bin, Biobuf *bout)
{
int seentok, waswhite, c;
seentok = 1;
waswhite = 0;
while((c = Bgetc(bin)) != Beof){
switch(c){
case ' ':
case '\t':
if(!waswhite){
seentok++;
waswhite = 1;
}
break;
case '\n':
seentok = 1;
break;
default:
waswhite = 0;
if(seentok == ntok){
Bprint(bout, str);
while((c = Bgetc(bin)) != Beof)
if(WHITESPACE(c))
break;
Bungetc(bin);
}
break;
}
Bputc(bout, c);
}
Bflush(bout);
}
void
main(int argc, char **argv)
{
Biobuf bin, bout;
ARGBEGIN{
}ARGEND;
if(argc != 2)
sysfatal("usage");
ntok = atoi(argv[0]);
str = argv[1];
Binit(&bin, 0, OREAD);
Binit(&bout, 1, OWRITE);
chgtok(&bin, &bout);
exits(0);
}
On Thu, Sep 17, 2009 at 10:23 AM, Rudolf Sykora <rudolf.syk...@gmail.com> wrote:
> Hello,
>
> simple task.
> I want to change the 2nd field on each line of a file, but preserve
> the spacing of the lines.
>
> If I do
> awk '{$2="hell"; print}' file
> the field gets changed, but all the spacing of the lines is gone; i.e.
> any space is now just ' ' like this:
> 1 3 4 8
> changes to
> 1 hell 4 8
> while I need
> 1 hell 4 8.
>
> Any help?
> Thanks
> Ruda
>
>
