Run the same command on a fleet of hosts. Three patterns: serial loop (simplest), GNU parallel (fastest), pssh (purpose-built).
Bash
HOSTS=(web1 web2 web3 db1)
# Serial — slow but easy to reason about
for h in "${HOSTS[@]}"; do
echo "─── $h ───"
ssh -n "$h" uptime
done
# Parallel with xargs (limit to 8 concurrent)
printf '%s\n' "${HOSTS[@]}" | xargs -P 8 -I{} ssh -n -o ConnectTimeout=5 {} uptime
# GNU parallel (cleaner output, must be installed)
parallel -j 8 ssh {} uptime ::: "${HOSTS[@]}"
# pssh — built specifically for this
pssh -h hosts.txt -i 'uptime'Save your own code snippets
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