Multiple arguments using xargs.

Question

I know xargs can take many arguments like so.

xargs -n5 -I{} echo {}

but how do I put the arguments in a particular location I want do something like.

xargs -n5 -I{} curl www.google.com/{1}/testing/{2}/{3}/works/{5}

How can something like that be achieved?

Solution 1

I don't think you can do this directly with xargs. Either use read as Costas suggests, or do:

xargs -n5 sh -c 'curl "http://www.google.com/${1}/testing/${2}/${3}/works/${5}"' curl-command

Or build the URL, then pass it to xargs:

awk '{printf "http://www.google.com/%s/testing/%s/%s/works/%s\n", $1, $2, $3, $5}' | \
  xargs -L1 curl 

Solution 2

You would almost think that you invented the syntax for GNU Parallel:

... | parallel -N5 curl www.google.com/{1}/testing/{2}/{3}/works/{5}

You get the added benefit that you will be running one curl per CPU.

GNU Parallel is a general parallelizer and makes is easy to run jobs in parallel on the same machine or on multiple machines you have ssh access to.

If you have 32 different jobs you want to run on 4 CPUs, a straight forward way to parallelize is to run 8 jobs on each CPU:

GNU Parallel instead spawns a new process when one finishes - keeping the CPUs active and thus saving time:

Installation

If GNU Parallel is not packaged for your distribution, you can do a personal installation, which does not require root access. It can be done in 10 seconds by doing this:

(wget -O - pi.dk/3 || curl pi.dk/3/ || fetch -o - http://pi.dk/3) | bash

For other installation options see http://git.savannah.gnu.org/cgit/parallel.git/tree/README

Learn more

See more examples: http://www.gnu.org/software/parallel/man.html

Watch the intro videos: https://www.youtube.com/playlist?list=PL284C9FF2488BC6D1

Walk through the tutorial: http://www.gnu.org/software/parallel/parallel_tutorial.html

Sign up for the email list to get support: https://lists.gnu.org/mailman/listinfo/parallel

Solution 3

system() function of awk can be used for this.

$ awk '{system("curl -v www.google.com/"$1"/testing/"$2"/"$3"/works/"$4)}' file.txt

Here file.txt contains the arguments to curl command.

Comments

[Kannan Mohan]

Can you provide more description about the problem

[Sten Kin]

I have a file that has lines like so A B C D E and I need to pass those arguments in a particular order to curl urls like www.google.com/A/testing/B/C/works/E