It's more easy using a command like this:

for f in cat servers.txt ; do ssh $f uname -a ; done

I usually do like this:

for f in cat servers.txt ; do echo "### $f ###" ; ssh $f uname -a ; done

The echo is to see which server is stuck, or cannot connect to it.

It's more easy using a command like this:

for f in `cat servers.txt`; do ssh $f uname -a; done

I usually do like this:

for f in `cat servers.txt`; do echo "### $f ###"; ssh $f uname -a; done

The echo is to see which server is stuck, or cannot connect to it.