Unified tail -f of a log file across multiple hosts via ssh.

multitail.sh

#!/bin/bash

# Example input and output (from the bash prompt):
# ./multitail.sh -H use@server -f /var/log/somelog.log
# ./multitail.sh -h "use@server use@server2 use@server3" -f "/var/log/somelogA.log /var/log/somelogB.log"
# ./multitail.sh --host "usu@server usu@server" --file "/var/log/logA.log"

# Based on https://gist.github.com/stantonk/5052027 and /usr/share/doc/util-linux/examples/getopt-parse.bash
# Note that we use `"$@"' to let each command-line parameter expand to a
# separate word. The quotes around `$@' are essential!
# We need TEMP as the `eval set --' would nuke the return value of getopt.
TEMP=$(getopt -o f:h: --long file:,server: \
     -n 'example.bash' -- "$@")
FILES=()
SERVERS=()

if [ $? != 0 ] ; then echo "Terminating..." >&2 ; exit 1 ; fi

# Note the quotes around `$TEMP': they are essential!
eval set -- "$TEMP"

while true ; do
	case "$1" in
		-f|--file) FILES+=($2) ; shift 2 ;;
		-h|--host) SERVERS+=($2) ; shift 2 ;;
		--) shift ; break ;;
		*) echo "Internal error!" ; exit 1 ;;
	esac
done

echo "Hit CTRL-C to stop"
sleep 0.5
PIDS=""
for host in ${HOSTS[*]}
do
	for file in ${FILES[*]}
	do
		CMD="tail -f ${file}"
		echo "ssh ${host} $CMD"
		ssh $host $CMD &
		PIDS="$PIDS $!"
	done
done

trap 'kill $PIDS' SIGINT

wait