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
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
Or: cat gem.list.1 | while read PKG; do sudo gem install $PKG; done
JD
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
-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@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
Andy Holt wrote:
[mailto:centos-bounces@centos.org] On Behalf Of neubyr
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
<snip> Screw xargs. Read an awk tutorial, maybe. Learn your tools.
awk '{name = $1; cmd = "sudo gem install " name; system( cmd);}' gem.list.1.
mark "yes, I do do awk..."
Thanks for the help everyone. I used awk as the gem.list file may contain version number in brackets - "rake (1.2)". I should have mentioned this before. I used 'awk $1' to get first column from each row. I liked all inputs, but I think I will try mark's awk solution here. Thanks again..
On Tue, May 17, 2011 at 8:30 AM, m.roth@5-cent.us wrote:
Andy Holt wrote:
[mailto:centos-bounces@centos.org] On Behalf Of neubyr
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
<snip> Screw xargs. Read an awk tutorial, maybe. Learn your tools.
awk '{name = $1; cmd = "sudo gem install " name; system( cmd);}' gem.list.1.
mark "yes, I do do awk..."
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