In Linux, you can use xargs -d, to quickly run the hostname command against four different servers with sequential names as follows:
echo -n 1,2,3,4 |xargs -d, -I{} ssh root@www{}.example.com hostname
It looks like the OSX xargs command does not support the delimiter parameter. Can you achieve the same result with a differently formatted echo, or through some other command-line utility?
Alternatively, you can always install GNU xargs through Homebrew and the GNU findutils package.
Install Homebrew:
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
Follow the instructions. Then install findutils:
brew install findutils
This will give you GNU xargs as gxargs, and you can use the syntax you're accustomed to from GNU/Linux. The same goes for other basic commands found in the findutils package such as gfind or glocate or gupdatedb, which have different BSD counterparts on OS X.
How about:
echo {1..4} | xargs -n1 -I{} ssh root@www{}.example.com hostname
From man xargs:
-n number
Set the maximum number of arguments taken from standard input for each invocation of utility.
You can also use tr in OSX to convert the commas to new lines and use xargs to enumerate through each item as follows:
echo -n 1,2,3,4 | tr -s ',' '\n' | xargs -I{} ssh root@www{}.example.com hostname
If you want it run in parallel, use GNU Parallel:
parallel ssh root@www{}.example.com hostname ::: {1..4}
with printf
$ printf '%s\n' 1 2 3 4 | xargs -I{} echo ssh root@www{}.example.com hostname
ssh root@www1.example.com hostname
ssh root@www2.example.com hostname
ssh root@www3.example.com hostname
ssh root@www4.example.com hostname
