From mboxrd@z Thu Jan  1 00:00:00 1970
MIME-Version: 1.0
In-Reply-To: <a560a5d00909170123u345b44b7od37524b5ff1786e1@mail.gmail.com>
References: <a560a5d00909170123u345b44b7od37524b5ff1786e1@mail.gmail.com>
Date: Thu, 17 Sep 2009 16:16:45 +0200
Message-ID: <56a297000909170716q6f2fe75dqf2abfbf89cb20265@mail.gmail.com>
From: Noah Evans <noah.evans@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Subject: Re: [9fans] awk help; not plan9 matter
Topicbox-Message-UUID: 709c7d10-ead5-11e9-9d60-3106f5b1d025

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) =3D=3D ' ' || (c) =3D=3D '\t' || (c) =3D=3D '\n=
')

void
chgtok(Biobuf *bin, Biobuf *bout)
{
	int seentok, waswhite, c;
	seentok =3D 1;
	waswhite =3D 0;

	while((c =3D Bgetc(bin)) !=3D Beof){
		switch(c){
		case ' ':
		case '\t':
			if(!waswhite){
				seentok++;
				waswhite =3D 1;
			}
			break;
		case '\n':
			seentok =3D 1;
			break;
		default:
			waswhite =3D 0;
			if(seentok =3D=3D ntok){
				Bprint(bout, str);
				while((c =3D Bgetc(bin)) !=3D Beof)
					if(WHITESPACE(c))
						break;
				Bungetc(bin);
			}
			break;		=09
		}
		Bputc(bout, c);
	}
	Bflush(bout);
}

void
main(int argc, char **argv)
{
	Biobuf bin, bout;

	ARGBEGIN{
	}ARGEND;
	if(argc !=3D 2)
		sysfatal("usage");
	ntok =3D atoi(argv[0]);
	str =3D argv[1];
	Binit(&bin, 0, OREAD);
	Binit(&bout, 1, OWRITE);
	chgtok(&bin, &bout);
	exits(0);=09
}




On Thu, Sep 17, 2009 at 10:23 AM, Rudolf Sykora <rudolf.sykora@gmail.com> w=
rote:
> 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
> =A0awk '{$2=3D"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 =A0 =A0 =A03 4 =A0 =A0 =A0 =A0 =A0 8
> changes to
> 1 hell 4 8
> while I need
> 1 =A0 =A0 =A0hell 4 =A0 =A0 =A0 =A0 =A0 8.
>
> Any help?
> Thanks
> Ruda
>
>