MerlinMake/warnIfAlreadyRunning.sh at master · TheCoderMerlin/MerlinMake · GitHub

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#!/bin/bash
# Check to see if target is already running
# If not, start target with the specified parameters
# If so, inform the user that the target is already running and that they may
#    resume with "fg"

# Usage: warnIfAlreadyRunning.sh <program> [--force-open] [arguments...]
# If --force-open is specified the program will be started, without checking to see
# if it is already running

# Because this script relies on the 'jobs' command, it MUST be sourced
# Reference: https://stackoverflow.com/questions/2683279/how-to-detect-if-a-script-is-being-sourced
if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
    echo "This script MUST be sourced."
    exit 1
fi

# Remember the target
target=$1

# Shift the target out so that we can start the application with the remaining
# arguments in $@
shift


# Determine if the user requested a forceOpen
# If so, note and remove the argument from the argument list
forceOpen=false
for argument in "$@"
do
    shift
    if [ "$argument" == "--force-open" ]
    then
	forceOpen=true
	continue
    else
	set -- "$@" "$argument"
    fi
done

# If forceOpen then simply start the program, otherwise continue to see
# if we're already running
if [ "$forceOpen" == "true" ]
then
    commandPath=`which $target`
    commandLine="$commandPath $@"
    eval $commandLine
else
    # Determine running processes (in all shells of this user)
    runningPids=`pidof $target`

    # The list is space delimited but we want it to be line delimited
    runningPids=`tr ' ' '\n' <<< "$runningPids"`

    # We now look for only those jobs in our current shell
    # with a matching pid
    jobs=`jobs -l`
    jobPids=`awk '{print $2}' <<< "$jobs"`

    # Iterate over the jobPids
    # If the pid of our process(es) matches that of a job in this shell
    # track it in an array
    # This is the intersection of all processes for the target and those
    # in the current shell
    pidsInShell=()
    while read jobPid; do
	while read runningPid; do
	    if [ $jobPid -eq $runningPid ]; then
		pidsInShell+=($jobPid)
	    fi
	done <<< "$runningPids"
    done <<< "$jobPids"

    # Iterate over only the relevant pids
    # Print the associated job description for each relevant pid
    for pidInShell in "${pidsInShell[@]}"
    do
	while read job; do
	    jobPid=`awk '{print $2}' <<< "$job"`
	    jobNumber=`awk -F'[][]' '{print $2}' <<< "$job"`
	    if [ $jobPid -eq $pidInShell ]; then
		echo -e "$target is already running in this shell: $job"
		echo -e "\tType 'fg $jobNumber' to resume"
	    fi
	done <<< $jobs
    done

    # If no jobs are already running, start a new instance of target with the specified
    # arguments
    # Otherwise, inform the user that they have the option of forcing the application to open
    if [ ${#pidsInShell[@]} -eq 0 ]; then
	commandPath=`which $target`
	echo "$target is not already running.  Starting $target."
	commandLine="$commandPath $@"
	eval $commandLine
    else
	echo "Alternatively, you may specify --force-open to force open a new instance."
    fi
fi