`ls -ltra | cut -f3` How would you cut?

frenchn00b · 06-11-2011, 01:10 AM

Hello,

Cut is not working for ls or ps aux or other where tab are not clearly defined. Another solutions are perl, awk, python, ... other ...

However I would consider that cut could work no, somehow. How would you cut it actually or what would be your universally working preference?

acid_kewpie · 06-11-2011, 01:14 AM

Sorry, what's the point of this thread? Just use awk.

not programming. Moved to Linux - Newbie.

frenchn00b · 06-11-2011, 01:27 AM

Quote:

Originally Posted by acid_kewpie

Sorry, what's the point of this thread? Just use awk.

not programming. Moved to Linux - Newbie.

It's philosophy about cut.

Awk is not a wise solution if for instance you code an application over sh and give it to a friend. If he has not awk, what you do? however all alternative to cut are done with some packages that may not be installed...

acid_kewpie · 06-11-2011, 01:36 AM

I don't think you're exactly the best judge of what is a wise solution...

druuna · 06-11-2011, 01:44 AM

Hi,

Besides acid_kewpie's comments: The cut command _does_ work! The problem is that the output of ls is space(s) separated and cut uses a tab as delimiter....

Using awk is the best/easiest solution in this case. I haven't come across a linux/unix distro that does not come with awk, if the actions done with awk are simple it doesn't matter if nawk, gawk, mawk or Xawk is used.

Hope this helps.

Valery Reznic · 06-12-2011, 11:17 PM

cut use as default field separator tab. But it can be changed with -d flag

evo2 · 06-12-2011, 11:57 PM

Hi,

this is slightly off topic from your initial post, but your second post you indicate that your motivation for the question is portability.

If you want portability, I'd suggest not parsing the output of ls. The output of 'ls -ltra' can differ significantly on different systems. Since you mention 'cut -f3' I guess you are trying to get a list of the file owners (at least that is the 3rd field on my system).

Code:

stat --format='%U' *

HTH,

Evo2.

ssrameez · 06-13-2011, 02:11 AM

Quote:

Originally Posted by frenchn00b

Hello,

ls -lart|cut -f3

You are missing the field separator.

ls -lart|cut -d ' ' -f3

This is working fine for me.

salasi · 06-13-2011, 02:14 AM

And, of course, read this.

frenchn00b · 06-13-2011, 02:30 AM

Quote:

Originally Posted by ssrameez

You are missing the field separator.

ls -lart|cut -d ' ' -f3

This is working fine for me.

For ps aux, it is the same story, it is not working also for portability:

Code:

ps aux | cut -f4

Solution is surely awk that is likely installed but if you take a 300MB just installed debian for instance (server install with the minimum) you will not have awk at all, nor perl. However "cut" is there, but it cannot easily crop the columns

evo2 · 06-13-2011, 02:50 AM

Hi,

this is similar to my post suggesting you use stat.

Quote:

Originally Posted by frenchn00b

For ps aux, it is the same story, it is not working also for portability

I'd suggest that the solution with ps, is not to parse its output (with cut, awk, perl or whatever), but to give the correct flags/options to ps so that it only ouputs the information that you are interested in.

Evo2.

ssrameez · 06-13-2011, 02:54 AM

I am not sure why are you missing the delimiter..

ps aux|cut -d' ' -f1

You can modify the field f1 or f4 accordingly.