service-manager

#!/bin/bash
print_info () {
    service="[your-service-name-here]"
cat  << EOF
Systemd is the init process on many modern linux systems. It starts up all the other proccesses that are needed. It also has the ability to run user defined things, such as services. These configurations are described in something called a unit file.

Generally, these are only for the system admins to run, but there is another feature, called user services. These allow any user to define their own service. These services, in their most basic form, run a single command when they start, which in our case, will be at boot.
User services are stored in ~/.config/systemd/user, and all end in ".service". You can find services created with this tool in there. More info about services can be found by running "man systemd.service"

To enable (auto start at boot) run systemctl --user enable $service
To start the service, run systemctl --user start $service
To restart the service, run systemctl --user restart $service. This is needed after any code changes
To view the status of the service, and its logs, run systemctl --user status $service

switch "enable" to "disable" to have it not auto start at boot
switch "start" to "stop" to stop the service

Script developed by Clark Bains. clark.bains@cmail.carleton.ca
EOF
    echo
}
create_unit () {
    echo "Creating Unit."
    while 
    read -p "Service Name: " service
    echo "$service" | grep -P "[^A-z\d\.-_]";
    do
        echo "Service name must be alphanumeric, and can additionally contain any of these symbols \"._-\""
    done
    #Not needed, but forcing a working dir will save headache for those who haven't done a great
    # job setting up include dirs.
    while 
    read -p "Working Dir: " workdir
    [[ ! -d $workdir || -z $workdir ]]
    do
        echo "Please provide a working directory"
    done
    cd $workdir
    workdir=`pwd`
    read -p "One line description: " description
    echo "Read the instructions on https://cwdc.scs.carleton.ca/foobar to figure out the correct execStart path"
    while true; do 
        while
        read -p "ExecStart: " execStart
        [ -z "$execStart" ]
        do
            echo "Please provide an ExecStart command"
        done

        IFS=' ' read -r -a execStartArr <<< "$execStart"
        fixedProg=${execStartArr[0]}

        # Try to fix if they passed in an interpreter without an absolute path
        if which ${execStartArr[0]} &> /dev/null ; then
            fixedProg=`which ${execStartArr[0]}`
        fi

        # Try to fix if they passed in the relative location of a script or binary
        if echo "$fixedProg" | grep -P "^\." &> /dev/null; then
            fixedProg=`realpath ${execStartArr[0]}`
        fi
        
        if [[ ! -f  $fixedProg ]]; then
            echo "Warn: Could not find program. Likely not put in correctly"
            edit=""
            while [[ -z $edit ]]; do
                read -p "[E]dit ExecStart, [C]ontinue without changing: " choice
                choice=`echo $choice | tr '[:upper:]' '[:lower:]'`
                case $choice in
                    c)
                        break;
                        ;;
                    e)
                        edit="y"
                        break;
                        ;;
                    *)
                        ;;
                esac;
            done;
         
            if [[ ! -z  $edit ]]; then
                continue
            fi
        fi
        
        if [[ $fixedProg != ${execStartArr[0]} ]]; then
            execStartArr[0]=$fixedProg
            newExecStart=$(IFS=" "; echo "${execStartArr[*]}")
            echo "Fixed Path. Command would now be: $newExecStart"
            edit=""
            while [[ -z $edit ]]; do
                read -p "[E]dit ExecStart, [A]ccept changes, [C]ontinue without changes: " choice
                choice=`echo $choice | tr '[:upper:]' '[:lower:]'`
                case $choice in
                    c)
                        break;
                        ;;
                    a)
                        execStart=$newExecStart
                        break;
                        ;;
                    e)
                        edit="y"
                        break;
                        ;;
                    *)
                        ;;
                esac;
            done;
         
            if [[ ! -z  $edit ]]; then
                continue
            fi
        fi
        break;
    done;
    unitFile="/tmp/$USER-${service}-unit"
cat >$unitFile <<EOF
[Unit]
Description=$description
After=network.target

[Service]
Type=simple
ExecStart=$execStart
WorkingDirectory=$workdir
RestartSec=1
Restart=always

[Install]
WantedBy=multi-user.target
EOF
    echo "Installing..."
    installFile="$HOME/.config/systemd/user/$service.service"
    backupFile="$HOME/`date +"%Y-%b-%e-%R:%S" | tr -d ' '`-$service.service"
    echo "Backup written to $backupFile"
    cat $unitFile | sed -E 's/^([^#].*=)$/#\1/g' > $backupFile

    if [[ -f $installFile ]]; 
    then
        echo "$installFile already exists. Please rename/delete it, then run"
        echo "  mv $backupFile $installFile"
    else
        cp $backupFile $installFile
        rm $backupFile
        echo "Installed to $installFile. Deleted Backup"
    fi

    echo ""
    echo "To enable (auto start at boot) run systemctl --user enable $service"
    echo "To start the service, run systemctl --user start $service"
    echo "To restart the service, run systemctl --user restart $service. This is needed after any code changes"
    echo "To view the status of the service, run systemctl --user status $service"
    echo "To trail the logs, run journalctl --user -xefu $service"
    echo
}
print_info;
echo
echo
if [ $SHELL == `which bash` ]; then
    echo "Please run using bash"
    exit 1
fi

if [[ $EUID -eq 0 ]]; then
   echo "This script should not be run as root" 
   exit 1
fi

# Might as well try?
loginctl enable-linger $USER 2> /dev/null
 
if [ ! -f /var/lib/systemd/linger/$USER ]; then
    echo "This account has not been setup to allow lingering processes"
    echo "Ask an admin to run \"loginctl enable-linger $USER\" on `hostname`"
    exit 1
fi

#if [ ! -d $HOME/.config/systemd/user/ ]; then
#    echo "Creating folder for systemd user unit files"
    mkdir -p $HOME/.config/systemd/user
#fi


create_unit