[sllug-members]: stderr + less

[Chad Lake]

On May 4, 2006, at 12:44 PM, Steve Dibb wrote:

> Is there a way to pipe stuff put out through stderr to less?
>
> I'm trying to do "foo | less" but with no arguments, it displays  
> the help file on stderr, and I can't figure out how to page it.

The problem is that pipes work by connecting stdout to stdin, so you  
have to have whatever data you want paged coming out of stdout.  If  
you don't care about merging the two, you can always just do "foo  
2>&1 | less" and then both stdout and stderr will go to the pipe.

However, if you only want to see what's on stderr, here's a trick  
that I use under bash, in a somewhat contrived example:

find . -print 2>&1 > /dev/null | less

In this instance, the 2>&1 comes *before* the "> /dev/null" part.   
This means that stderr is dup'd to stdout before stdout is redirected  
to /dev/null (or wherever).   So, for whatever the find outputs, the  
stuff spit out to stderr will wind up going to regular stdout (and to  
the pipe) and the stuff spit out to stdout will go to the redirect  
(in this case /dev/null).

Oh, and of course you can always do something like this:

foo 2>/tmp/errorstuff
less /tmp/errorstuff
rm /tmp/errorstuff

if you really want to keep it simple.  :)


				-c