Running commands on several remote hosts using ssh and xargs

There are a few different ways to run commands on groups or clusters of remote nodes, depending upon how complex the command.

Assuming your machines are named "node01" - "node22" :


# Run a command in parallel on all remote nodes
# results come back in random order as they are received.
pdsh -w "node[01-22]" df


# pdsh allows some more complex listings of hosts
pdsh -w "node04,node[06-09]" reboot


# Run a command sequentially on all remote nodes
# slow, but results come back in order
seq -w 1 22 | xargs -I '{}' ssh node'{}' df


# Run a command in parallel on all remote nodes without pdsh
seq -w 1 22 | xargs -P 22 -I '{}' ssh node'{}' df


# Run a command in parallel needing pipes on the remote host
# Otherwise, pipes are processed locally
seq -w 1 22 | xargs -P 22 -I '{}' ssh node'{}' \
"ps afx > \`hostname\`.txt"


# Run a command in parallel needing root
# sudo requires a tty, hence we pop up xterm windows
seq -w 1 22 | xargs -P 22 -I '{}' xterm -e \
"ssh -t node'{}' sudo gdm-restart"


# Run a command in parallel needing root and pipes on the remote host
seq -w 1 22 | xargs -P 22 -I '{}' xterm -e \
"ssh -t node'{}' sudo bash -c \"echo 3 > /proc/sys/vm/drop_caches\""

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