Re: [ADD TO FAQ] : cut : using space as input delimiter

[seb_kramm]

Hello, thanks for your response,

Bob Proulx a écrit :
> seb_kramm wrote:
> > I have search about an hour on how to tell 'cut' to use space as input 
> > delimiter, finally found out alone ! Below is the question I was about to 
> > post, and the solution. I suggest adding this "trick" to the FAQ, or even 
> > to the manual.
>
> I will add something to the FAQ since this has come up a few times.

Thanks for the future users

> > I have a generated numeric data file, to be plotted using gnuplot. The 
> > fields are separated with spaces. Before plotting, I need to do some basic 
> > line/text processing, using 'cut' and 'join'.
>
> 'cut' isn't the best tool to cut fields.  'awk' is better.

Yes, even though I am a windows user ;-), I heard about awk, but I needed something 
quick, and didn't want to spent time on learning the syntax. My needs seemed simple. 
But I'll take a look at awk for sure as soon as I have some time.

> > # data
> > 1  1.1  1.3  1.4
> > 2  1.2  1.5  1.6
> > ...
> >
> > Unfortunatly, I can't manage to use the space character as input separator 
> > for 'cut'. I read the coreutils FAQ, the manual (5.3.0), p.43, but I 
> > understand (and tried) that this is not possible.
>
> The problem is that the fields are separated by TWO spaces not one
> space.  This means that in the above there are SEVEN fields not four.
> Field 2 that you want to cut is an empty field.  You would want field
> 3 instead.

Ah. Is that a problem ? I mean, when I talk about the space character as a 
field-separator, to me, it's the same if there is 1 or 2 or more spaces. Like in a 
source code, it doesn't matter how much spaces or tabs there are.

> > Quote the whole 'd' option:
>
> Yes.  Or quote just the delimiter.  Either way is exactly the same to
> [...]

> > Another solution is using 'unexpand' to replace spaces by tabs
>
> Yes.  'cut' was really designed to work on TAB separated fields.
> Using 'unexpand' to get to TAB separated fields is in the spirit of
> the way cut is designed to work.  Today if 'cut' were designed again
> it would probably be using a comma by default because .csv files are
> more common today than TAB separate fields.  I would be inclined to go
> this way because then things are more obvious because the delimiters
> are visible.

I agree, the only reason I used space as a delimitor is that it is the default 
separator for gnuplot, and that I was to lazy to find the command to tell it to use 
another separator. But I really better like .csv style.

Sebastien Kramm