topic Re: ls and pipe in Operating System - HP-UX

ls and pipe

mobidyc — Thu, 12 Apr 2007 07:58:21 GMT

Hello,

I have a stupid question and it troubles me.

Why the stdout format of 'ls' is changed through a piped command?

if i do an 'ls' for example, i view all files in a column view.
'ls |more' view a file by line.

so questions are:
- why ?
- is there a way for bypass it ? (without rewrite the output)

Regards,
Cedrick Gaillard

Re: ls and pipe

Dennis Handly — Thu, 12 Apr 2007 08:02:54 GMT

>Why the stdout format of 'ls' is changed through a piped command?

Probably they make the -1 option the default so that when you feed the piped out to a filter, you get one at a time.

Re: ls and pipe

mobidyc — Thu, 12 Apr 2007 08:09:43 GMT

Hello,

i've just re-read the manpage and i've found the '-C' flag.

this flag allow the multicolum view through a pipe ;)

Regards,
Cedrick Gaillard

Re: ls and pipe

Hein van den Heuvel — Thu, 12 Apr 2007 08:13:08 GMT

RTFM (Read The Fine Manpage)

For for multicolumn to a pipe use: ls -C
Also check out: ls -m

Please note how the actual multicolumn format depends on the file name length and terminal width. Try stty cols xxx and repeas an ls.
- how wide is a pipe?
- how would a program behind a pipe have to deal with unpredicatable format?

Cheers,
Hein.

Re: ls and pipe

James R. Ferguson — Thu, 12 Apr 2007 08:14:14 GMT

Hi Cedrick:

You can force the preservation of the column view by doing:

# ls -x | more

Regards!

...JRF...

Re: ls and pipe

Torsten. — Thu, 12 Apr 2007 08:17:20 GMT

Just to add this:
the flag is used with "ls", because "ls" is filling the pipe and "ls" is responsible for the output format, e.g.
# ls -C | more
or
# ls -x | more
this is up to what you want to get.

Re: ls and pipe

Peter Nikitka — Thu, 12 Apr 2007 08:26:46 GMT

Hi,

to summarize the answers above:
it's not the pipe, which modifies the output (look at ls >tmpfile!) but the tty:
Without tty you get unmodified output.

mfG Peter