[[!meta title="How to find and execute stuff on all hosts?"]]

## Motivation

Assume that you are managing a pretty large infrastructure of hosts,
sometimes there is a need to execute a command on all of them.

The big question is, where to find out, which hosts exist.

## Solution

The usual approach is to invent some kind of centralised daemon that collects
or searches for available hosts. There is a way simpler solution available in
my situation, which may help you as well:
We do have a monitoring infrastructure, to which all hosts transmit their
configuration. The configuration is stored containing the full hostname
(like **foo.bar.local.ch**) plus the .cfg suffix.

Thus a script that can be used to execute something on all hosts (sequentially though)
can look like this:

    for host in $(ssh monitoring01 "cd /opt/icinga/etc/hosts.d; ls"); do
        host=${host%.cfg}
        ssh "root@$host" "$@"
    done

[[!tag sysadmin localch unix]]