max-uptime-keeper

#!/bin/bash

#DEBUG=true;
#VERBOSE=true;

###########################
##
##  Install this file as a cron job by running it as
##  max-uptime -i | --install
##
###########################

LogDir='/var/log/max-uptime-keeper';
[[ -d "$LogDir" ]] || mkdir -p "$LogDir"; # create the dir if it's missing

fCurrentUptime="$LogDir/uptime.current"
fMaxUptime="$LogDir/uptime.max"
fLogUptime="$LogDir/uptime.log"
touch "$fCurrentUptime"
touch "$fMaxUptime"
touch "$fLogUptime"

: ${DEBUG:=false};
: ${VERBOSE:=false};

ScriptName=`readlink -f "$0"`;
User=$USER;

UT=`uptime -p`
read UTs J </proc/uptime

InstallCronStub() {
    if [[ $1 == '-i' ]] || [[ $1 == '--install' ]]; then
        local _User=${2:-$User};
        local _Group=$_User;
        if [[ $_User == 'nobody' ]]; then _User='nogroup'; fi
        sudo chown ${_User}:$_Group "$LogDir"     # make sure the installed user can write to the log dir
        sudo chown ${_User}:$_Group "$ScriptName" # make sure the installed user can run the script
        sudo chmod 755 "$ScriptName"              # make sure only the installed user can write to the script
        # if any logfiles exist make sure the installed user owns them
        [[ -f $fCurrentUptime ]] && sudo chown ${_User}:$_Group "$fCurrentUptime"
        [[ -f $fMaxUptime ]]     && sudo chown ${_User}:$_Group "$fMaxUptime"
        [[ -f $fLogUptime ]]     && sudo chown ${_User}:$_Group "$fLogUptime"
        # if any logfiles exist make sure everyone can write to them
        sudo chmod 777 "$LogDir"     # make sure everyone write to the log dir
        [[ -f $fCurrentUptime ]] && sudo chmod 666 "$fCurrentUptime"
        [[ -f $fMaxUptime ]]     && sudo chmod 666 "$fMaxUptime"
        [[ -f $fLogUptime ]]     && sudo chmod 666 "$fLogUptime"
        cat <<-EOF #| sudo tee /etc/cron.d/max-uptime-keeper >/dev/null
		# update max-uptime records every minute
		# m h dom mon dow user  command
		  * *  *   *   *  $_User $ScriptName
EOF
    fi
}

ReadUptimeFiles() {
    cUTs=0; cUT=0; mUTs=0; mUT=0; lUTs=0; lUT=0;
    read cUTs cUT <"$fCurrentUptime"
    read mUTs mUT <"$fMaxUptime"
    while read LOG; do : ; done <"$fLogUptime";
    : ${cUTs:=0}; : ${cUT:=0};
    : ${mUTs:=0}; : ${mUT:=0};
    : ${lUTs:=0}; : ${lUT:=0};
}

vecho() { # only outputs if VERBOSE is true
    if $VERBOSE; then
        echo "$@"
    fi
}

PrintUptimes() {
    if $DEBUG; then
        echo -en "\n====================\n"
        echo "Uptime     Now = $UTs : $UT";
        echo "Uptime Current = $cUTs";
        echo "Uptime     Max = $mUTs";
        echo "Uptime     Log = $LOG";
    fi
}

DumpFiles() {
    if $DEBUG; then
        echo -en "\n====================\nCurrent\n====================\n"
        cat "$fCurrentUptime"
        echo -en "\n====================\nMax\n====================\n"
        cat "$fMaxUptime"
        echo -en "\n====================\nLog\n====================\n"
        cat "$fLogUptime"
        echo
        echo
    fi
}

WriteUptimesToFile() {
    if [[ $1 == $fCurrentUptime ]]; then # Replace Current Uptime
        echo "$UTs : $UT" >"$fCurrentUptime";
    elif [[ $1 == $fLogUptime ]]; then # Append to log
        vecho "$ScriptName: Logging Uptime from Last Boot in $fLogUptime";
        echo " : $cUTs $cUT" >>"$fLogUptime";
        echo -n "Booted "`uptime -s` >>"$fLogUptime";
    elif [[ $1 == $fMaxUptime ]]; then # Replace Max Uptime
        vecho "$ScriptName: Recording New Max Uptime in $fMaxUptime";
        echo "$cUTs $cUT" >"$fMaxUptime";
    fi
}

UpdateUptimeFiles() {
    #  if this is a low uptime write the old Uptime to the Log
    if (( ${UTs%.*} < ${cUTs%.*} )); then # log at every boot
        WriteUptimesToFile "$fLogUptime";

        # if last is greater than the max uptime write to max uptime file
        if (( ${cUTs%.*} > ${mUTs%.*} )); then
            WriteUptimesToFile "$fMaxUptime";
        fi
    fi
}

if (( ${#@} >0 )); then InstallCronStub "$@"; fi

ReadUptimeFiles
#UTs=0; # Uncomment this line to force "new boot" behaviour

if $DEBUG; then
    PrintUptimes
fi

#  Store the current Uptime
WriteUptimesToFile "$fCurrentUptime"

UpdateUptimeFiles

if $DEBUG; then
    ReadUptimeFiles
    PrintUptimes
    DumpFiles
fi