Generic Bash File to start and stop scripts using nohup and pid file

server.sh

#!/bin/bash

# 
# Generic file to start and stop server using nohup and pid file
#
# Author:  Marcos Lin
# Date:    15 Dec 2014
# License: MIT License
#


log_dir="./run"
process_name="restserver.py"
process_base=$(basename $process_name .py)
process_out="$log_dir/$process_base.out"
process_pid="$log_dir/$process_base.pid"

#
# Check command line option.
#
action=$1
shift
params=$@

help_needed () {
    echo "$0 <start|status|stop|restart>" 1>&2
    exit 1
}

if [ -z "$action" ]; then
    echo "Error: missing required parameter" 1>&2
    help_needed
elif [[ ! "$action" =~ ^start|status|stop|restart$ ]]; then
    echo "Error: '$action' is not valid option" 1>&2
    help_needed
fi


#
# Check process
#
running_pid ()  {
    if [ -r "$process_pid" ]; then
        local pid=$(cat $process_pid)
        local proc=$(ps w -p $pid | grep $process_name)
        if [ -n "$proc" ]; then
            echo $pid
        else
            local pid_search=$(search_pid)
            if [ -n "$pid_search" ]; then
                echo $pid_search
            else
                # pid file exists but no matching process found.  Delete the pid file
                rm "$process_pid"
            fi
        fi
    else
        local pid_search=$(search_pid)
        if [ -n "$pid_search" ]; then
            echo $pid_search
        fi
    fi
}

search_pid() {
    local pid=$(ps aux | grep $process_name | grep -v grep | awk "{ print \$2 }")
    if [ -n "$pid" ]; then
        # Write data
        if [ ! -r "$process_pid" ]; then
            echo $pid > $process_pid
        fi
        # Return PID found
        echo $pid
    fi
}


kill_process () {
    local pid=$1
    local proc=$pid
    local retries=1
    local max_retries=4
    local retries_force=$(($max_retries-1))
    echo -n "Stopping process $pid "
    while [ $retries -lt $max_retries -a -n "$proc" ]; do
        echo -n "."

        # Force kill if last retry
        if [ $retries -lt $retries_force ]; then
            kill $pid > /dev/null
        else
            kill -9 $pid > /dev/null
        fi

        # Check if process was killed
        proc=$(running_pid)
        if [ -z "$proc" ]; then
            if [ -r "$process_pid" ]; then
                rm $process_pid
            fi
            retries=$max_retries
        else
            retries=$((retries+1))
            sleep 1
        fi
    done
    echo ""

    if [ -n "$proc" ]; then
        echo "Error: failed to kill process running as pid $pid" 1>&2
        return 1
    fi
}

#
# Actions
#
pid_running=$(running_pid)
start () {
    if [ -z "$pid_running" ]; then
        source ./venv/bin/activate
        nohup $process_name $params &> $process_out &
        sleep 1
        local running_pid=$(search_pid)
        if [ -n "$running_pid" ]; then
            echo $! > $process_pid
            echo "Process started with pid $(cat $process_pid)"
        else
            echo "Error: Process failed to start"
            cat $process_out
            return 1
        fi
    else
        echo "Process already running as pid $pid_running"
    fi
}

status () {
    if [ -z "$pid_running" ]; then
        echo "Process not running"
    else
        echo "Process running as pid $pid_running"
    fi
}

stop () {
    if [ -n "$pid_running" ]; then
        kill_process $pid_running
        local kill_process_result=$?
        echo "

$(date +"%Y-%m-%dT%H:%M:%S") server stop callled
        " >> $process_out
        return $kill_process_result
    else
        echo "No process running"
        return 1
    fi
}

restart () {
    stop
    if [ $? -ne 0 ]; then
        return 1
    fi
    pid_running=$(running_pid)
    start
}

# Execute action
$action