CentOS - May 2011 - xargs with max each line / argument

How do I pass xargs input one line at a time to subsequent command?
For example I want to install rubygems by reading a text file as shown
below, however the arguments are getting passed all at once to the
'gem install' command. I hace tried -L (max-lines) and -n (max args)
options, but it didn't work. What's missing here?? Any help?

$ cat gem.list.1
mkrf
rake
xmlparser

$ awk '{ print $0 }' gem.list.1 | xargs -L 1 -0 -I name sudo gem install
name
ERROR:  could not find gem mkrf
rake
xmlparser
 locally or in a repository


thanks,
neuby.r

On 5/17/11 12:36 AM, neubyr wrote:
> How do I pass xargs input one line at a time to subsequent command?
> For example I want to install rubygems by reading a text file as shown
> below, however the arguments are getting passed all at once to the
> 'gem install' command. I hace tried -L (max-lines) and -n (max
args)
> options, but it didn't work. What's missing here?? Any help?
>
> $ cat gem.list.1
> mkrf
> rake
> xmlparser
>
> $ awk '{ print $0 }' gem.list.1 | xargs -L 1 -0 -I name sudo gem
install name
> ERROR:  could not find gem mkrf
> rake
> xmlparser
>   locally or in a repository
The -0 to xargs says your items will be null-terminated, but they aren't. 
And
you don't really need awk to pick the first field out of a one-field line,
just
cat it or let xargs read it directly with <gem.list.1

-- 
    Les Mikesell
     lesmikesell at gmail.com

On Tue, May 17, 2011 at 12:36:08AM -0500, neubyr wrote:
> How do I pass xargs input one line at a time to subsequent command?
xargs is the wrong tool for this job.
> $ awk '{ print $0 }' gem.list.1 | xargs -L 1 -0 -I name sudo gem
install name
while read line
do
  sudo gem install $line
done < gem.list.1

-- 

rgds
Stephen

> -----Original Message-----
> From: centos-bounces at centos.org 
> [mailto:centos-bounces at centos.org] On Behalf Of neubyr
> Sent: 17/05/2011 06:36
> To: CentOS mailing list
> Subject: [CentOS] xargs with max each line / argument
> 
> How do I pass xargs input one line at a time to subsequent command?
> For example I want to install rubygems by reading a text file as shown
> below, however the arguments are getting passed all at once to the
> 'gem install' command. I hace tried -L (max-lines) and -n (max
args)
> options, but it didn't work. What's missing here?? Any help?
> 
> $ cat gem.list.1
> mkrf
> rake
> xmlparser
> 
> $ awk '{ print $0 }' gem.list.1 | xargs -L 1 -0 -I name sudo 
> gem install name
> ERROR:  could not find gem mkrf
> rake
> xmlparser
>  locally or in a repository
> 
> 
> thanks,
> neuby.r
Hi.

As others have mentioned, a simple cat or use of < into xargs will simplify
things.  The max-args switch _is_ the one you are
looking for:

--max-args=max-args, -n max-args

Spceifically:

cat gem.list.1 | xargs --max-args=1 sudo gem install

will do what you want, I think - please test it first.  You could add
--interactive to xargs to help with this, or even just:

cat gem.list.1 | xargs --max-args=1 echo sudo gem install

which will just dump the commands that would be run (using echo).

hth   Andy