#!/bin/bash
PROCESS_MATCH="\.\/php-fpm"
PROCESS="./php-fpm"
INSTANCES=$1
PIDDIR="/tmp/php-fpm.pid"
INTERVAL=10
mkdir -p "$PIDDIR"
while true; do
    PIDS=$(pgrep -f "$PROCESS_MATCH" | grep -v $$)
    RUNNING=0
    rm -f "$PIDDIR"/*
    for pid in $PIDS; do
        RUNNING=$((RUNNING + 1))
        echo "$pid" > "$PIDDIR/$pid.pid"
    done
    if [ "$RUNNING" -lt "$INSTANCES" ]; then
        TO_START=$((INSTANCES - RUNNING))
        for i in $(seq 1 "$TO_START"); do
            "$PROCESS"
            sleep 1
        done
    fi
    sleep "$INTERVAL"
done