shell start / stop for python script

Question

I have a simple python script i need to start and stop and i need to use a start.sh and stop.sh script to do it.

I have start.sh:

#!/bin/sh

scri         


        

Answer 1

I don't have a unix box on at the moment, so i can't test this, but it should be fairly simple to get the idea.

start.sh:

if [ -e ./temp ]
then
  pid=`cat temp`
  echo "Process already exists; $pid"
else
  script='/path/to/my/script.py'
  echo 'starting $script with nohup'
  nohup /usr/bin/python $script &
  echo $! > temp
fi

stop.sh:

if [ -e ./temp ]
then
  pid=`cat temp`
  echo "killing $pid"
  kill -15 $PID
  rm temp
else
  echo "Process not started"
fi

Try this out.

Answer 2

The "correct" approach would probably be to have your script write its pid to a file in /var/run, and clear it out when you kill the script. If changing the script is not an option, have a look at start-stop-daemon.

If you want to continue with the grep-like approach, have a look at proctools. They're built in on most GNU/Linux machines and readily available on BSD including OS X:

pkill -f /path/to/my/script.py

Answer 3

ps aux | grep "/path/to/my/script.py"

will return both the pid for the instance of script.py and also for this instance of grep. That'll probably be why you're getting a no such process: by the time you get around to killing the grep, it's already dead.

Answer 4

init-type scripts are useful for this. This is very similar to one I use. You store the pid in a file, and when you want to check if it's running, look into the /proc filesystem.

#!/bin/bash

script_home=/path/to/my
script_name="$script_home/script.py"
pid_file="$script_home/script.pid"

# returns a boolean and optionally the pid
running() {
    local status=false
    if [[ -f $pid_file ]]; then
        # check to see it corresponds to the running script
        local pid=$(< "$pid_file")
        local cmdline=/proc/$pid/cmdline
        # you may need to adjust the regexp in the grep command
        if [[ -f $cmdline ]] && grep -q "$script_name" $cmdline; then
            status="true $pid"
        fi
    fi
    echo $status
}

start() {
    echo "starting $script_name"
    nohup "$script_name" &
    echo $! > "$pid_file"
}

stop() {
    # `kill -0 pid` returns successfully if the pid is running, but does not
    # actually kill it.
    kill -0 $1 && kill $1
    rm "$pid_file"
    echo "stopped"
}

read running pid < <(running)

case $1 in 
    start)
        if $running; then
            echo "$script_name is already running with PID $pid"
        else
            start
        fi
        ;;
    stop)
        stop $pid
        ;;
    restart)
        stop $pid
        start
        ;;
    status)
        if $running; then
            echo "$script_name is running with PID $pid"
        else
            echo "$script_name is not running"
        fi
        ;;
    *)  echo "usage: $0 <start|stop|restart|status>"
        exit
        ;;
esac

Answer 5

It is because ps aux |grep SOMETHING also finds the grep SOMETHING process, because SOMETHING matches. After the execution the grep is finished, so it cannot find it.

Add a line: ps aux | grep -v grep | grep YOURSCRIPT

Where -v means exclude. More in man grep.