X-Git-Url: https://zdv2.bktei.com/gitweb/EVA-2020-02.git/blobdiff_plain/c78a1a206b48ce414f23f2eb8b3639e76fc0731a..d59a052d726ec948737314b6abec6e2073cf7a37:/exec/bkgpslog?ds=inline

diff --git a/exec/bkgpslog b/exec/bkgpslog
index 5cfa7cc..1705ab2 100755
--- a/exec/bkgpslog
+++ b/exec/bkgpslog
@@ -1,106 +1,1335 @@
 #!/bin/bash
 
-# Author: Steven Baltakatei Sandoval
+# Desc: Records gps data until midnight
+# Author: Steven Baltakatei Sandoval; License: GPLv3+
+# Usage: bkgpslog -o [output dir]
 
-#== Variable Initialization ==
+#==BEGIN Define script parameters==
+## Logging Behavior parameters
+BUFFER_TTL="300"; # time between file writes
+SCRIPT_TTL_TE="day"; # (day|hour)
+#### TZ="UTC"; export TZ; # Default time zone; overridden by '--time-zone=[str]' option
+DIR_TMP_DEFAULT="/dev/shm"; # Default parent of working directory
 
-#== Global constants ==
-PATH="/usr/local/bin/:$PATH"    # Add default OpenTimestamps path to PATH (necessary if cron used to call this script)
-PATH="/opt/bktei:$PATH"         # Add default baltakatei script install directory to PATH (necessary for other bk scripts)
-SCRIPT_HOSTNAME=$(hostname)     # Save hostname of system running this script.
-SCRIPT_VERSION="bkgpslog 0.0.1" # Define version of script.
-SCRIPT_TIME_SHORT="$(date +%Y%m%dT%H%M%S%z)" # Save current date & time in ISO-8601 format.
-SCRIPT_DATE_SHORT="$(date +%Y%m%d)"          # Save current date in ISO-8601 format.
-#DIROUT1="/home/pi/Sync/Evanescent_Location"  # Define output directory.
+SCRIPT_TIME_START=$(date +%Y%m%dT%H%M%S.%N);
+PATH="$HOME/.local/bin:$PATH";   # Add "$(systemd-path user-binaries)" path in case apps saved there
+SCRIPT_HOSTNAME=$(hostname);     # Save hostname of system running this script.
+SCRIPT_VERSION="0.4.4-alpha";          # Define version of script.
+SCRIPT_NAME="bkgpslog";          # Define basename of script file.
+SCRIPT_URL="https://gitlab.com/baltakatei/ninfacyzga-01"; # Define wesite hosting this script.
+AGE_VERSION="1.0.0-beta2";       # Define version of age (encryption program)
+AGE_URL="https://github.com/FiloSottile/age/releases/tag/v1.0.0-beta2"; # Define website hosting age.
+
+declare -Ag appRollCall # Associative array for storing app status
+declare -Ag fileRollCall # Associative array for storing file status
+declare -Ag dirRollCall # Associative array for storing dir status
+declare -a argRecPubKeys # for processArguments function
+# declare -a errorHistory # for correcting buffer lag
+
+## Initialize variables
+OPTION_VERBOSE=""; OPTION_ENCRYPT=""; OPTION_COMPRESS=""; OPTION_TMPDIR="";
+errResetx10e3=0; BUFFER_TTL_ADJ_FLOAT="";
+### PID Control factors
+K_P=10; # Gain for compensating buffer round lag
+T_I=2; # Consider this number of past buffer rounds to eliminate error
+T_D=1; # Predict value this number of buffer rounds into the future
+
+#===BEGIN Declare local script functions===
+checkapp() {
+    # Desc: If arg is a command, save result in assoc array 'appRollCall'
+    # Usage: checkapp arg1 arg2 arg3 ...
+    # Input: global assoc. array 'appRollCall'
+    # Output: adds/updates key(value) to global assoc array 'appRollCall'
+    local returnState    
+    #echo "DEBUG:$(date +%S.%N)..Starting checkapp function."
+    #echo "DEBUG:args: $@"
+    #echo "DEBUG:returnState:$returnState"
+
+    #===Process Args===
+    for arg in "$@"; do
+	#echo "DEBUG:processing arg:$arg"
+	if command -v "$arg" 1>/dev/null 2>&1; then # Check if arg is a valid command
+	    appRollCall[$arg]="true";
+	    #echo "DEBUG:appRollCall[$arg]:"${appRollCall[$arg]}
+	    if ! [ "$returnState" = "false" ]; then returnState="true"; fi
+	else
+	    appRollCall[$arg]="false"; returnState="false";
+	fi
+    done
+    
+    #for key in "${!appRollCall[@]}"; do echo "DEBUG:$key => ${appRollCall[$key]}"; done
+    #echo "DEBUG:evaluating returnstate. returnState:"$returnState
+
+    #===Determine function return code===
+    if [ "$returnState" = "true" ]; then
+	#echo "DEBUG:checkapp returns true for $arg";
+	return 0;
+    else
+	#echo "DEBUG:checkapp returns false for $arg";
+	return 1;
+    fi
+} # Check that app exists
+checkfile() {
+    # Desc: If arg is a file path, save result in assoc array 'fileRollCall'
+    # Usage: checkfile arg1 arg2 arg3 ...
+    # Input: global assoc. array 'fileRollCall'
+    # Output: adds/updates key(value) to global assoc array 'fileRollCall';
+    # Output: returns 0 if app found, 1 otherwise
+    local returnState
+
+    #===Process Args===
+    for arg in "$@"; do
+	#echo "DEBUG:processing arg:$arg"
+	if [ -f "$arg" ]; then
+	    fileRollCall["$arg"]="true";
+	    #echo "DEBUG:fileRollCall[\"$arg\"]:"${fileRollCall["$arg"]}
+	    if ! [ "$returnState" = "false" ]; then returnState="true"; fi
+	else
+	    fileRollCall["$arg"]="false"; returnState="false";
+	fi
+    done
+
+    #for key in "${!fileRollCall[@]}"; do echo "DEBUG:fileRollCall key [$key] is:${fileRollCall[$key]}"; done
+    #echo "DEBUG:evaluating returnstate. returnState:"$returnState
+    
+    #===Determine function return code===
+    if [ "$returnState" = "true" ]; then
+	#echo "DEBUG:checkapp returns true for $arg";
+	return 0;
+    else
+	#echo "DEBUG:checkapp returns false for $arg";
+	return 1;
+    fi
+} # Check that file exists
+checkdir() {
+    # Desc: If arg is a dir path, save result in assoc array 'dirRollCall'
+    # Usage: checkdir arg1 arg2 arg3 ...
+    # Input: global assoc. array 'dirRollCall'
+    # Output: adds/updates key(value) to global assoc array 'dirRollCall';
+    # Output: returns 0 if app found, 1 otherwise
+    local returnState
+
+    #===Process Args===
+    for arg in "$@"; do
+	#echo "DEBUG:processing arg:$arg"
+	if [ -d "$arg" ]; then
+	    dirRollCall["$arg"]="true";
+	    #echo "DEBUG:dirRollCall[\"$arg\"]:"${dirRollCall["$arg"]}
+	    if ! [ "$returnState" = "false" ]; then returnState="true"; fi
+	elif [ "$arg" = "" ]; then
+	    dirRollCall["$arg"]="false"; returnState="false";
+	else
+	    returnState="false";
+	fi
+    done
+
+    #for key in "${!dirRollCall[@]}"; do echo "DEBUG:dirRollCall key [$key] is:${dirRollCall[$key]}"; done
+    #echo "DEBUG:evaluating returnstate. returnState:"$returnState
+    
+    #===Determine function return code===
+    if [ "$returnState" = "true" ]; then
+	#echo "DEBUG:checkapp returns true for $arg";
+	return 0;
+    else
+	#echo "DEBUG:checkapp returns false for $arg";
+	return 1;
+    fi
+} # Check that dir exists
+
+# Yell, Die, Try Three-Fingered Claw technique
+# Ref/Attrib: https://stackoverflow.com/a/25515370
+yell() { echo "$0: $*" >&2; }
+die() { yell "$*"; exit 111; }
+try() { "$@" || die "cannot $*"; }
 
-#== Function Definitions ==
 echoerr() {
     echo "$@" 1>&2; # Define stderr echo function.
 } # Define stderr message function.
 showUsage() {
     echoerr "USAGE:"
-    echoerr "    bkgpslog.sh [ options ]"
+    echoerr "    bkgpslog [ options ]"
     echoerr
     echoerr "OPTIONS:"
     echoerr "    -h, --help"
     echoerr "            Display help information."
-    echoerr
     echoerr "    --version"
     echoerr "            Display script version."
-    echoerr
     echoerr "    -v, --verbose"
     echoerr "            Display debugging info."
-    echoerr
-    echoerr "    -o, --output [ directory ]"
+    echoerr "    -e, --encrypt"
+    echoerr "            Encrypt output."
+    echoerr "    -r, --recipient [ string pubkey ]"
+    echoerr "            Specify recipient. May be age or ssh pubkey."
+    echoerr "            May be specified multiple times for multiple pubkeys."
+    echoerr "            See https://github.com/FiloSottile/age"
+    echoerr "    -o, --output [ path dir ]"
     echoerr "            Specify output directory to save logs."
+    echoerr "    -c, --compress"
+    echoerr "            Compress output with gzip (before encryption if enabled)."
+    echoerr "    -z, --time-zone"
+    echoerr "            Specify time zone. (ex: \"America/New_York\")"
+    echoerr "    -t, --temp-dir [path dir]"
+    echoerr "            Specify parent directory for temporary working directory."
+    echoerr "            Default: \"/dev/shm\""
+    echoerr "    -R, --recipient-dir [path dir]"
+    echoerr "            Specify directory containing files whose first lines are"
+    echoerr "            to be interpreted as pubkey strings (see \\'-r\\' option)."
+    echoerr "    -b, --buffer-ttl [integer]"
+    echoerr "            Specify custom buffer period in seconds (default: 300 seconds)"
+    echoerr "    -B, --script-ttl [integer]"
+    echoerr "            Specify custom script time-to-live in seconds (default: \"day\")"
+    echoerr
+    echoerr "EXAMPLE: (bash script lines)"
+    echoerr "/bin/bash bkgpslog -v -e -c \\"
+    echoerr "-z \"UTC\" -t \"/dev/shm\" \\"
+    echoerr "-r age1mrmfnwhtlprn4jquex0ukmwcm7y2nxlphuzgsgv8ew2k9mewy3rs8u7su5 \\"
+    echoerr "-r age1ala848kqrvxc88rzaauc6vc5v0fqrvef9dxyk79m0vjea3hagclswu0lgq \\"
+    echoerr "-o ~/Sync/Location"
 } # Display information on how to use this script.
 showVersion() {
     echoerr "$SCRIPT_VERSION"
 } # Display script version.
 vbm() {
-    if [ $OPTION_VERBOSE -eq "true" ]; then
-	echoerr "$@"
+    # Usage: vbm "DEBUG:verbose message here"
+    # Description: Prints verbose message ("vbm") to stderr if OPTION_VERBOSE is set to "true".
+    # Input:
+    #   - OPTION_VERBOSE  variable set by processArguments function. (ex: "true", "false")
+    #   - "$@"            positional arguments fed to this function.
+    # Output: stderr
+    # Script function dependencies: echoerr
+    # External function dependencies: echo
+    # Last modified: 2020-04-11T23:57Z
+    # Last modified by: Steven Baltakatei Sandoval
+    # License: GPLv3+
+    # Ref./Attrib:
+
+    if [ "$OPTION_VERBOSE" = "true" ]; then
+	FUNCTION_TIME=$(date --iso-8601=ns); # Save current time in nano seconds.
+	echoerr "[$FUNCTION_TIME] ""$*"; # Display argument text.
     fi
+
+    # End function
+    return 0; # Function finished.
 } # Verbose message display function.
 processArguments() {
     while [ ! $# -eq 0 ]; do   # While number of arguments ($#) is not (!) equal to (-eq) zero (0).
-	echoerr "DEBUG:Starting processArguments while loop."
-	echoerr "DEBUG:Provided arguments are:""$@"
+	#echoerr "DEBUG:Starting processArguments while loop."
+	#echoerr "DEBUG:Provided arguments are:""$*"
 	case "$1" in
-	    --h | --help) showUsage; exit 1;; # Display usage.
+	    -h | --help) showUsage; exit 1;; # Display usage.
 	    --version) showVersion; exit 1;; # Show version
-	    --v | --verbose) OPTION_VERBOSE="true"; vbm "DEBUG:Verbose mode enabled.";; # Enable verbose mode.
-	    --o | --output) if [ -d "$2" ]; then DIROUT1="$2"; fi ;; # Define output directory.
-	    *) echoerr "ERROR: Unrecognized argument."; exit 1;; # Handle unrecognized options.
+	    -v | --verbose) OPTION_VERBOSE="true"; vbm "DEBUG:Verbose mode enabled.";; # Enable verbose mode.
+	    -o | --output) if [ -d "$2" ]; then DIR_OUT="$2"; vbm "DEBUG:DIR_OUT:$DIR_OUT"; shift; fi ;; # Define output directory.
+	    -e | --encrypt) OPTION_ENCRYPT="true"; vbm "DEBUG:Encrypted output mode enabled.";; # Enable encryption
+	    -r | --recipient) OPTION_RECIPIENTS="true"; argRecPubKeys+=("$2"); vbm "STATUS:pubkey added:""$2"; shift;; # Add recipients
+	    -c | --compress) OPTION_COMPRESS="true"; vbm "DEBUG:Compressed output mode enabled.";; # Enable compression
+	    -z | --time-zone) try setTimeZoneEV "$2"; shift;; # Set timestamp timezone
+	    -t | --temp-dir) OPTION_TMPDIR="true" && argTempDirPriority="$2"; shift;; # Set time zone
+	    -R | --recipient-dir) OPTION_RECIPIENTS="true"; OPTION_RECDIR="true" && argRecDir="$2"; shift;; # Add recipient watch dir
+	    -b | --buffer-ttl) OPTION_CUSTOM_BUFFERTTL="true" && argCustomBufferTTL="$2"; shift;; # Set custom buffer period (default: 300 seconds)
+	    -B | --script-ttl) OPTION_CUSTOM_SCRIPTTTL_TE="true" && argCustomScriptTTL="$2"; shift;; # Set custom script TTL (default: "day")
+	    *) echoerr "ERROR: Unrecognized argument: $1"; echoerr "STATUS:All arguments:$*"; exit 1;; # Handle unrecognized options.
 	esac
 	shift
     done
 } # Argument Processing
-checkExecutables() {
+setTimeZoneEV(){
+    # Desc: Set time zone environment variable TZ
+    # Usage: setTimeZoneEV arg1
+    # Input: arg1: 'date'-compatible timezone string (ex: "America/New_York")
+    #        TZDIR env var (optional; default: "/usr/share/zoneinfo")
+    # Output: exports TZ
+    #         exit code 0 on success
+    #         exit code 1 on incorrect number of arguments
+    #         exit code 2 if unable to validate arg1
+    # Depends: yell, printenv, bash 5
+    # Tested on: Debian 10
+    ARG1="$1"
+    local tzDir returnState
+    if ! [[ $# -eq 1 ]]; then
+	yell "ERROR:Invalid argument count.";
+	return 1;
+    fi
+
+    # Read TZDIR env var if available
+    if printenv TZDIR 1>/dev/null 2>&1; then
+	tzDir="$(printenv TZDIR)";
+    else
+	tzDir="/usr/share/zoneinfo";
+    fi
     
-} # Check that certain executables exist.
+    # Validate TZ string
+    if ! [[ -f "$tzDir"/"$ARG1" ]]; then
+	yell "ERROR:Invalid time zone argument.";
+	return 2;
+    else
+    # Export ARG1 as TZ environment variable
+	TZ="$ARG1" && export TZ && returnState="true";
+    fi
 
-main() {
-    processArguments # Process arguments.
-    checkExecutables "gpspipe" # Confirm that executables necessary to run are available.
-} # Main function.
+    # Determine function return code
+    if [ "$returnState" = "true" ]; then
+	return 0;
+    fi
+} # Exports TZ environment variable
+timeUntilNextDay(){
+    # Desc: Report seconds until next day.
+    # Version: 1.0.0
+    # Output: stdout: integer seconds until next day
+    # Output: exit code 0 if stdout > 0; 1 if stdout = 0; 2 if stdout < 0
+    # Usage: timeUntilNextDay
+    # Usage: if ! myTTL="$(timeUntilNextDay)"; then yell "ERROR in if statement"; exit 1; fi
+    # Depends: date 8, echo 8, yell, try
+    
+    local returnState TIME_CURRENT TIME_NEXT_DAY SECONDS_UNTIL_NEXT_DAY
+
+    TIME_CURRENT="$(date --iso-8601=seconds)" ; # Produce `date`-parsable current timestamp with resolution of 1 second.
+    TIME_NEXT_DAY="$(date -d "$TIME_CURRENT next day" --iso-8601=date)"; # Produce timestamp of beginning of tomorrow with resolution of 1 second.
+    SECONDS_UNTIL_NEXT_DAY="$(( $(date +%s -d "$TIME_NEXT_DAY") - $(date +%s -d "$TIME_CURRENT") ))" ; # Calculate seconds until closest future midnight (res. 1 second).
+    if [[ "$SECONDS_UNTIL_NEXT_DAY" -gt 0 ]]; then
+	returnState="true";
+    elif [[ "$SECONDS_UNTIL_NEXT_DAY" -eq 0 ]]; then
+	returnState="warning_zero";
+	yell "WARNING:Reported time until next day exactly zero.";
+    elif [[ "$SECONDS_UNTIL_NEXT_DAY" -lt 0 ]]; then
+	returnState="warning_negative";
+	yell "WARNING:Reported time until next day is negative.";
+    fi
+
+    try echo "$SECONDS_UNTIL_NEXT_DAY"; # Report
+    
+    # Determine function return code
+    if [[ "$returnState" = "true" ]]; then
+	return 0;
+    elif [[ "$returnState" = "warning_zero" ]]; then
+	return 1;
+    elif [[ "$returnState" = "warning_negative" ]]; then
+	return 2;
+    fi
+} # Report seconds until next day
+timeUntilNextHour(){
+    # Desc: Report seconds until next hour
+    # Version 1.0.0
+    # Output: stdout: integer seconds until next hour
+    # Output: exit code 0 if stdout > 0; 1 if stdout = 0; 2 if stdout < 0
+    # Usage: timeUntilNextHour
+    # Usage: if ! myTTL="$(timeUntilNextHour)"; then yell "ERROR in if statement"; exit 1; fi
+    
+    local returnState TIME_CURRENT TIME_NEXT_HOUR SECONDS_UNTIL_NEXT_HOUR
+    TIME_CURRENT="$(date --iso-8601=seconds)"; # Produce `date`-parsable current timestamp with resolution of 1 second.
+    TIME_NEXT_HOUR="$(date -d "$TIME_CURRENT next hour" --iso-8601=hours)"; # Produce `date`-parsable current time stamp with resolution of 1 second.
+    SECONDS_UNTIL_NEXT_HOUR="$(( $(date +%s -d "$TIME_NEXT_HOUR") - $(date +%s -d "$TIME_CURRENT") ))"; # Calculate seconds until next hour (res. 1 second).
+    if [[ "$SECONDS_UNTIL_NEXT_HOUR" -gt 0 ]]; then
+	returnState="true";
+    elif [[ "$SECONDS_UNTIL_NEXT_HOUR" -eq 0 ]]; then
+	returnState="warning_zero";
+	yell "WARNING:Reported time until next hour exactly zero.";
+    elif [[ "$SECONDS_UNTIL_NEXT_HOUR" -lt 0 ]]; then
+	returnState="warning_negative";
+	yell "WARNING:Reported time until next hour is negative.";
+    fi
+
+    try echo "$SECONDS_UNTIL_NEXT_HOUR"; # Report
+    
+    # Determine function return code
+    if [[ "$returnState" = "true" ]]; then
+	return 0;
+    elif [[ "$returnState" = "warning_zero" ]]; then
+	return 1;
+    elif [[ "$returnState" = "warning_negative" ]]; then
+	return 2;
+    fi
+} # Report seconds until next hour
+dateTimeShort(){
+    # Desc: Timestamp without separators (YYYYmmddTHHMMSS+zzzz)
+    # Usage: dateTimeShort ([str date])
+    # Version 1.1.0
+    # Input: arg1: 'date'-parsable timestamp string (optional)
+    # Output: stdout: timestamp (ISO-8601, no separators)
+    # Depends: yell
+    local TIME_CURRENT TIME_CURRENT_SHORT
+
+    argTime="$1";
+    # Get Current Time
+    TIME_CURRENT="$(date --iso-8601=seconds)" ; # Produce `date`-parsable current timestamp with resolution of 1 second.
+    # Decide to parse current or supplied date
+    ## Check if time argument empty
+    if [[ -z "$argTime" ]]; then
+	## T: Time argument empty, use current time
+	TIME_INPUT="$TIME_CURRENT";
+    else
+	## F: Time argument exists, validate time
+	if date --date="$argTime" 1>/dev/null 2>&1; then
+	    ### T: Time argument is valid; use it
+	    TIME_INPUT="$argTime";
+	else
+	    ### F: Time argument not valid; exit
+	    yell "ERROR:Invalid time argument supplied. Exiting."; exit 1;
+	fi
+    fi
+    # Construct and deliver separator-les date string
+    TIME_CURRENT_SHORT="$(date -d "$TIME_INPUT" +%Y%m%dT%H%M%S%z)";
+    echo "$TIME_CURRENT_SHORT";
+} # Get YYYYmmddTHHMMSS±zzzz
+dateShort(){
+    # Desc: Date without separators (YYYYmmdd)
+    # Usage: dateShort ([str date])
+    # Version: 1.1.0
+    # Input: arg1: 'date'-parsable timestamp string (optional)
+    # Output: stdout: date (ISO-8601, no separators)
+    # Depends: yell
+    local TIME_CURRENT DATE_CURRENT_SHORT
+
+    argTime="$1";
+    # Get Current Time
+    TIME_CURRENT="$(date --iso-8601=seconds)" ; # Produce `date`-parsable current timestamp with resolution of 1 second.
+    # Decide to parse current or supplied date
+    ## Check if time argument empty
+    if [[ -z "$argTime" ]]; then
+	## T: Time argument empty, use current time
+	TIME_INPUT="$TIME_CURRENT";
+    else
+	## F: Time argument exists, validate time
+	if date --date="$argTime" 1>/dev/null 2>&1; then
+	    ### T: Time argument is valid; use it
+	    TIME_INPUT="$argTime";
+	else
+	    ### F: Time argument not valid; exit
+	    yell "ERROR:Invalid time argument supplied. Exiting."; exit 1;
+	fi
+    fi
+    # Construct and deliver separator-les date string    
+    DATE_CURRENT_SHORT="$(date -d "$TIME_INPUT" +%Y%m%d)"; # Produce separator-less current date with resolution 1 day.
+    echo "$DATE_CURRENT_SHORT";
+} # Get YYYYmmdd
+timeDuration(){
+    # Desc: Given seconds, output ISO-8601 duration string
+    # Ref/Attrib: ISO-8601:2004(E), §4.4.4.2 Representations of time intervals by duration and context information
+    # Note: "1 month" ("P1M") is assumed to be "30 days" (see ISO-8601:2004(E), §2.2.1.2)
+    # Usage: timeDuration [1:seconds] ([2:precision])
+    # Version: 1.0.3
+    # Input: arg1: seconds as base 10 integer >= 0  (ex: 3601)
+    #        arg2: precision level (optional; default=2)
+    # Output: stdout: ISO-8601 duration string (ex: "P1H1S", "P2Y10M15DT10H30M20S")
+    #         exit code 0: success
+    #         exit code 1: error_input
+    #         exit code 2: error_unknown
+    # Example: 'timeDuration 111111 3' yields 'P1DT6H51M'
+    # Depends: date 8 (gnucoreutils), yell, 
+    local returnState argSeconds argPrecision remainder precision witherPrecision
+    local fullYears fullMonths fullDays fullHours fullMinutes fullSeconds
+    local displayYears displayMonths displayDays displayHours displayMinutes displaySeconds
+    local hasYears hasMonths hasDays hasHours hasMinutes hasSeconds
+    
+    argSeconds="$1"; # read arg1 (seconds)
+    argPrecision="$2"; # read arg2 (precision)
+    precision=2; # set default precision
+
+    # Check that between one and two arguments is supplied
+    if ! { [[ $# -ge 1 ]] && [[ $# -le 2 ]]; }; then
+	yell "ERROR:Invalid number of arguments:$# . Exiting.";
+	returnState="error_input"; fi
+
+    # Check that argSeconds provided
+    if [[ $# -ge 1 ]]; then
+	## Check that argSeconds is a positive integer
+	if [[ "$argSeconds" =~ ^[[:digit:]]+$ ]]; then
+   	    :
+	else
+	    yell "ERROR:argSeconds not a digit.";
+	    returnState="error_input";
+	fi
+    else
+	yell "ERROR:No argument provided. Exiting.";
+	exit 1;
+    fi
 
+    # Consider whether argPrecision was provided
+    if  [[ $# -eq 2 ]]; then
+	# Check that argPrecision is a positive integer
+	if [[ "$argPrecision" =~ ^[[:digit:]]+$ ]] && [[ "$argPrecision" -gt 0 ]]; then
+	precision="$argPrecision";
+	else
+	    yell "ERROR:argPrecision not a positive integer. (is $argPrecision ). Leaving early.";
+	    returnState="error_input";
+	fi;
+    else
+	:
+    fi;
+    
+    remainder="$argSeconds" ; # seconds
+    ## Calculate full years Y, update remainder
+    fullYears=$(( remainder / (365*24*60*60) ));
+    remainder=$(( remainder - (fullYears*365*24*60*60) ));
+    ## Calculate full months M, update remainder
+    fullMonths=$(( remainder / (30*24*60*60) ));
+    remainder=$(( remainder - (fullMonths*30*24*60*60) ));
+    ## Calculate full days D, update remainder
+    fullDays=$(( remainder / (24*60*60) ));
+    remainder=$(( remainder - (fullDays*24*60*60) ));
+    ## Calculate full hours H, update remainder
+    fullHours=$(( remainder / (60*60) ));
+    remainder=$(( remainder - (fullHours*60*60) ));
+    ## Calculate full minutes M, update remainder
+    fullMinutes=$(( remainder / (60) ));
+    remainder=$(( remainder - (fullMinutes*60) ));
+    ## Calculate full seconds S, update remainder
+    fullSeconds=$(( remainder / (1) ));
+    remainder=$(( remainder - (remainder*1) ));
+    ## Check which fields filled
+    if [[ $fullYears -gt 0 ]]; then hasYears="true"; else hasYears="false"; fi
+    if [[ $fullMonths -gt 0 ]]; then hasMonths="true"; else hasMonths="false"; fi
+    if [[ $fullDays -gt 0 ]]; then hasDays="true"; else hasDays="false"; fi
+    if [[ $fullHours -gt 0 ]]; then hasHours="true"; else hasHours="false"; fi
+    if [[ $fullMinutes -gt 0 ]]; then hasMinutes="true"; else hasMinutes="false"; fi
+    if [[ $fullSeconds -gt 0 ]]; then hasSeconds="true"; else hasSeconds="false"; fi
+    
+    ## Determine which fields to display (see ISO-8601:2004 §4.4.3.2)
+    witherPrecision="false"
+    
+    ### Years
+    if $hasYears && [[ $precision -gt 0 ]]; then
+	displayYears="true";
+	witherPrecision="true";
+    else
+	displayYears="false";
+    fi;
+    if $witherPrecision; then ((precision--)); fi;
+    
+    ### Months
+    if $hasMonths && [[ $precision -gt 0 ]]; then
+	displayMonths="true";
+	witherPrecision="true";
+    else
+	displayMonths="false";
+    fi;
+    if $witherPrecision && [[ $precision -gt 0 ]]; then
+	displayMonths="true";
+    fi;
+    if $witherPrecision; then ((precision--)); fi;
+
+    ### Days
+    if $hasDays && [[ $precision -gt 0 ]]; then
+	displayDays="true";
+	witherPrecision="true";
+    else
+	displayDays="false";
+    fi;
+    if $witherPrecision && [[ $precision -gt 0 ]]; then
+	displayDays="true";
+    fi;
+    if $witherPrecision; then ((precision--)); fi;
+
+    ### Hours
+    if $hasHours && [[ $precision -gt 0 ]]; then
+	displayHours="true";
+	witherPrecision="true";
+    else
+	displayHours="false";
+    fi;
+    if $witherPrecision && [[ $precision -gt 0 ]]; then
+	displayHours="true";
+    fi;
+    if $witherPrecision; then ((precision--)); fi;
+
+    ### Minutes
+    if $hasMinutes && [[ $precision -gt 0 ]]; then
+	displayMinutes="true";
+	witherPrecision="true";
+    else
+	displayMinutes="false";
+    fi;
+    if $witherPrecision && [[ $precision -gt 0 ]]; then
+	displayMinutes="true";
+    fi;
+    if $witherPrecision; then ((precision--)); fi;
+
+    ### Seconds
+
+    if $hasSeconds && [[ $precision -gt 0 ]]; then
+	displaySeconds="true";
+	witherPrecision="true";
+    else
+	displaySeconds="false";
+    fi;
+    if $witherPrecision && [[ $precision -gt 0 ]]; then
+	displaySeconds="true";
+    fi;
+    if $witherPrecision; then ((precision--)); fi;
+
+    ## Determine whether or not the "T" separator is needed to separate date and time elements
+    if ( $displayHours || $displayMinutes || $displaySeconds); then
+	displayDateTime="true"; else displayDateTime="false"; fi
+    
+    ## Construct duration output string
+    OUTPUT="P"
+    if $displayYears; then
+	OUTPUT=$OUTPUT$fullYears"Y"; fi
+    if $displayMonths; then
+	OUTPUT=$OUTPUT$fullMonths"M"; fi
+    if $displayDays; then
+	OUTPUT=$OUTPUT$fullDays"D"; fi
+    if $displayDateTime; then
+	OUTPUT=$OUTPUT"T"; fi
+    if $displayHours; then
+	OUTPUT=$OUTPUT$fullHours"H"; fi
+    if $displayMinutes; then
+	OUTPUT=$OUTPUT$fullMinutes"M"; fi
+    if $displaySeconds; then
+	OUTPUT=$OUTPUT$fullSeconds"S"; fi
+
+    ## Output duration string to stdout
+    echo "$OUTPUT" && returnState="true";
+
+    #===Determine function return code===
+    if [ "$returnState" = "true" ]; then
+	return 0;
+    elif [ "$returnState" = "error_input" ]; then
+	yell "ERROR:input";
+	return 1;
+    else
+	yell "ERROR:Unknown";
+	return 2;
+    fi
+
+} # Get duration (ex: PT10M4S )
+displayMissing() {
+    # Desc: Displays missing apps, files, and dirs
+    # Usage: displayMissing
+    # Input: associative arrays: appRollCall, fileRollCall, dirRollCall
+    # Output: stderr messages
+    #==BEGIN Display errors==
+    #===BEGIN Display Missing Apps===
+    missingApps="Missing apps  :"
+    #for key in "${!appRollCall[@]}"; do echo "DEBUG:$key => ${appRollCall[$key]}"; done
+    for key in "${!appRollCall[@]}"; do
+	value="${appRollCall[$key]}"
+	if [ "$value" = "false" ]; then
+	    #echo "DEBUG:Missing apps: $key => $value";
+	    missingApps="$missingApps""$key "
+	    appMissing="true"
+	fi
+    done
+    if [ "$appMissing" = "true" ]; then  # Only indicate if an app is missing.
+	echo "$missingApps" 1>&2;
+    fi
+    #===END Display Missing Apps===
 
+    #===BEGIN Display Missing Files===
+    missingFiles="Missing files:"
+    #for key in "${!fileRollCall[@]}"; do echo "DEBUG:$key => ${fileRollCall[$key]}"; done
+    for key in "${!fileRollCall[@]}"; do
+	value="${fileRollCall[$key]}"
+	if [ "$value" = "false" ]; then
+	    #echo "DEBUG:Missing files: $key => $value";
+	    missingFiles="$missingFiles""$key "
+	    fileMissing="true"
+	fi
+    done
+    if [ "$fileMissing" = "true" ]; then  # Only indicate if an app is missing.
+	echo "$missingFiles" 1>&2;
+    fi
+    #===END Display Missing Files===
 
+    #===BEGIN Display Missing Directories===
+    missingDirs="Missing dirs:"
+    #for key in "${!dirRollCall[@]}"; do echo "DEBUG:$key => ${dirRollCall[$key]}"; done
+    for key in "${!dirRollCall[@]}"; do
+	value="${dirRollCall[$key]}"
+	if [ "$value" = "false" ]; then
+	    #echo "DEBUG:Missing dirs: $key => $value";
+	    missingDirs="$missingDirs""$key "
+	    dirMissing="true"
+	fi
+    done
+    if [ "$dirMissing" = "true" ]; then  # Only indicate if an dir is missing.
+	echo "$missingDirs" 1>&2;
+    fi
+    #===END Display Missing Directories===
 
+    #==END Display errors==
+} # Display missing apps, files, dirs
+magicSetScriptTTL() {
+    #Desc: Sets script_TTL seconds from provided time_element string argument
+    #Usage: magicSetScriptTTL [str time_element]
+    #Input: arg1: string (Ex: SCRIPT_TTL_TE; "day" or "hour")
+    #Output: var: SCRIPT_TTL (integer seconds)
+    #Depends: timeUntilNextHour, timeUntilNextDay
+    local argTimeElement
+    argTimeElement="$1"
+    if [[ "$argTimeElement" = "day" ]]; then
+	    # Set script lifespan to end at start of next day
+	if ! SCRIPT_TTL="$(timeUntilNextDay)"; then
+	    if [[ "$SCRIPT_TTL" -eq 0 ]]; then
+	    ((SCRIPT_TTL++)); # Add 1 because 0 would cause 'timeout' to never timeout.
+	    else
+	    yell "ERROR: timeUntilNextDay exit code $?"; exit 1;
+	    fi;
+	fi;
+    elif [[ "$argTimeElement" = "hour" ]]; then
+	# Set script lifespan to end at start of next hour
+	if ! SCRIPT_TTL="$(timeUntilNextHour)"; then
+	    if [[ "$SCRIPT_TTL" -eq 0 ]]; then
+		((SCRIPT_TTL++)); # Add 1 because 0 would cause 'timeout' to never timeout.
+	    else
+		yell "ERROR: timeUntilNextHour exit code $?"; exit 1;
+	    fi;
+	fi;
+    else
+	yell "ERROR:Invalid argument for setScriptTTL function:$argTimeElement"; exit 1;
+    fi
+} # Seconds until next (day|hour).
+checkMakeTar() {
+    # Desc: Checks that a valid tar archive exists, creates one otherwise
+    # Usage: checkMakeTar [ path ]
+    # Version: 1.0.1
+    # Input: arg1: path of tar archive
+    # Output: exit code 0 : tar readable
+    #         exit code 1 : tar missing; created
+    #         exit code 2 : tar not readable; moved; replaced
+    # Depends: try, tar, date
+    local PATH_TAR returnFlag0 returnFlag1 returnFlag2
+    PATH_TAR="$1"
 
+    # Check if file is a valid tar archive
+    if tar --list --file="$PATH_TAR" 1>/dev/null 2>&1; then
+	## T1: return success
+	returnFlag0="tar valid";
+    else
+	## F1: Check if file exists
+	if [[ -f "$PATH_TAR" ]]; then
+	    ### T: Rename file
+	    try mv "$PATH_TAR" "$PATH_TAR""--broken--""$(date +%Y%m%dT%H%M%S)" && \
+		returnFlag1="tar moved";
+	else
+	    ### F: -
+	    :
+	fi
+	## F2: Create tar archive, return 0
+	try tar --create --file="$PATH_TAR" --files-from=/dev/null && \
+	    returnFlag2="tar created";
+    fi
+    
+    # Determine function return code
+    if [[ "$returnFlag0" = "tar valid" ]]; then
+	return 0;
+    elif [[ "$returnFlag2" = "tar created" ]] && ! [[ "$returnFlag1" = "tar moved" ]]; then
+	return 1; # tar missing so created
+    elif [[ "$returnFlag2" = "tar created" ]] && [[ "$returnFlag1" = "tar moved" ]]; then
+	return 2; # tar not readable so moved; replaced
+    fi
+} # checks if arg1 is tar; creates one otherwise
+appendArgTar(){
+    # Desc: Writes first argument to temporary file with arguments as options, then appends file to tar
+    # Usage: appendArgTar "$(echo "Data to be written.")" [name of file to be inserted] [tar path] [temp dir] ([cmd1] [cmd2] [cmd3] [cmd4]...)
+    # Version: 1.0.3
+    # Input: arg1: data to be written
+    #        arg2: file name of file to be inserted into tar
+    #        arg3: tar archive path (must exist first)
+    #        arg4: temporary working dir
+    #        arg5+: command strings (ex: "gpsbabel -i nmea -f - -o kml -F - ")
+    # Output: file written to disk
+    # Example: decrypt multiple large files in parallel
+    #          appendArgTar "$(cat /tmp/largefile1.gpg)" "largefile1" $HOME/archive.tar /tmp "gpg --decrypt" &
+    #          appendArgTar "$(cat /tmp/largefile2.gpg)" "largefile2" $HOME/archive.tar /tmp "gpg --decrypt" &
+    #          appendArgTar "$(cat /tmp/largefile3.gpg)" "largefile3" $HOME/archive.tar /tmp "gpg --decrypt" &
+    # Depends: bash 5
+    # Ref/Attrib: Using 'eval' to construct command strings https://askubuntu.com/a/476533
 
-if [[ -d "$DIROUT1" ]] && command -v "gpspipe" 1>/dev/null 2>/dev/null ; then
-    while true; do
-	#echoerr "DEBUG:Starting while loop."
-	# Update time constants
-	TIME_CURRENT="$(date --iso-8601=seconds)" ;
-	#echoerr "DEBUG:TIME_CURRENT is:""$TIME_CURRENT" ;
-	TIME_CURRENT_SHORT="$(date -d "$TIME_CURRENT" +%Y%m%dT%H%M%S%z)"
-	#echoerr "DEBUG:TIME_CURRENT_SHORT is""$TIME_CURRENT_SHORT"
-	DATE_CURRENT="$(date -d "$TIME_CURRENT" --iso-8601=date)" ;
-	#echoerr "DEBUG:DATE_CURRENT is:""$DATE_CURRENT" ;
-	DATE_CURRENT_SHORT="$(date -d "$TIME_CURRENT" +%Y%m%d)" ;
-	#echoerr "DEBUG:DATE_CURRENT is:""$DATE_CURRENT_SHORT" ;
-	DATE_TOMORROW="$(date -d "$TIME_CURRENT next day" --iso-8601=date)" ;
-	#echoerr "DEBUG:DATE_TOMORROW is:""$DATE_TOMORROW" ;
-	TIME_NEXT_MIDNIGHT="$(date -d "$DATE_TOMORROW" --iso-8601=seconds)" ;
-	#echoerr "DEBUG:TIME_NEXT_MIDNIGHT is:""$TIME_NEXT_MIDNIGHT" ;
-	SECONDS_UNTIL_NEXT_MIDNIGHT="$((  $(date +%s -d "$TIME_NEXT_MIDNIGHT") - $(date +%s -d "$TIME_CURRENT")  ))" ;
-	#echoerr "DEBUG:SECONDS_UNTIL_NEXT_MIDNIGHT is:""$SECONDS_UNTIL_NEXT_MIDNIGHT" ;
-	if [ "$SECONDS_UNTIL_NEXT_MIDNIGHT" -eq 0 ]; then echoerr "WARNING:Is it exactly midnight?" ; continue; fi ; # Exit loop early if equal to 0 because "timeout 0s" never ends.
-	if [ "$SECONDS_UNTIL_NEXT_MIDNIGHT" -lt 0 ]; then echoerr "ERROR:Time until midnight error." ; exit 1; fi ; # Exit script if equal to 0 because "timeout 0s" never ends.
+    # Save function name
+    local FN="${FUNCNAME[0]}";
+    #yell "DEBUG:STATUS:$FN:Finished appendArgTar()."
+    
+    # Set file name
+    if ! [ -z "$2" ]; then FILENAME="$2"; else yell "ERROR:$FN:Not enough arguments."; exit 1; fi
+    
+    # Check tar path is a file
+    if [ -f "$3" ]; then TAR_PATH="$3"; else yell "ERROR:$FN:Tar archive arg not a file."; exit 1; fi
 	
-	# Update output file names.
-	DIROUTN="$DIROUT1" ;
-	FILEOUTN="$DATE_CURRENT_SHORT""..""$(hostname)""_location.nmea" ;
+    # Check temp dir arg
+    if ! [ -z "$4" ]; then TMP_DIR="$4"; else yell "ERROR:$FN:No temporary working dir set."; exit 1; fi
+    
+    # Set command strings
+    if ! [ -z "$5" ]; then CMD1="$5"; else CMD1="tee /dev/null "; fi # command string 1
+    if ! [ -z "$6" ]; then CMD2="$6"; else CMD2="tee /dev/null "; fi # command string 2
+    if ! [ -z "$7" ]; then CMD3="$7"; else CMD3="tee /dev/null "; fi # command string 3
+    if ! [ -z "$8" ]; then CMD4="$8"; else CMD4="tee /dev/null "; fi # command string 4
+
+    # Input command
+    CMD0="echo \"\$1\""
+
+    # # Debug
+    # yell "DEBUG:STATUS:$FN:CMD0:$CMD0"
+    # yell "DEBUG:STATUS:$FN:CMD1:$CMD1"
+    # yell "DEBUG:STATUS:$FN:CMD2:$CMD2"
+    # yell "DEBUG:STATUS:$FN:CMD3:$CMD3"
+    # yell "DEBUG:STATUS:$FN:CMD4:$CMD4"
+    # yell "DEBUG:STATUS:$FN:FILENAME:$FILENAME"
+    # yell "DEBUG:STATUS:$FN:TAR_PATH:$TAR_PATH"
+    # yell "DEBUG:STATUS:$FN:TMP_DIR:$TMP_DIR"
+    
+    # Write to temporary working dir
+    eval "$CMD0"" | ""$CMD1"" | ""$CMD2"" | ""$CMD3"" | ""$CMD4" > "$TMP_DIR"/"$FILENAME";
+
+    # Append to tar
+    try tar --append --directory="$TMP_DIR" --file="$TAR_PATH" "$FILENAME";
+    #yell "DEBUG:STATUS:$FN:Finished appendArgTar()."
+} # Append Bash var to file appended to Tar archive
+appendFileTar(){
+    # Desc: Processes first file and then appends to tar
+    # Usage: appendFileTar [file path] [name of file to be inserted] [tar path] [temp dir] ([cmd1] [cmd2] [cmd3] [cmd4]...)
+    # Version: 1.0.2
+    # Input: arg1: path of file to be (processed and) written
+    #        arg2: name to use for file inserted into tar
+    #        arg3: tar archive path (must exist first)
+    #        arg4: temporary working dir
+    #        arg5+: command strings (ex: "gpsbabel -i nmea -f - -o kml -F - ")
+    # Output: file written to disk
+    # Example: decrypt multiple large files in parallel
+    #          appendFileTar /tmp/largefile1.gpg "largefile1" $HOME/archive.tar /tmp "gpg --decrypt" &
+    #          appendFileTar /tmp/largefile2.gpg "largefile2" $HOME/archive.tar /tmp "gpg --decrypt" &
+    #          appendFileTar /tmp/largefile3.gpg "largefile3" $HOME/archive.tar /tmp "gpg --decrypt" &
+    # Depends: bash 5
+
+    # Save function name
+    local FN="${FUNCNAME[0]}";
+    #yell "DEBUG:STATUS:$FN:Finished appendFileTar()."
+    
+    # Set file name
+    if ! [ -z "$2" ]; then FILENAME="$2"; else yell "ERROR:$FN:Not enough arguments."; exit 1; fi
+    # Check tar path is a file
+    if [ -f "$3" ]; then TAR_PATH="$3"; else yell "ERROR:$FN:Tar archive arg not a file."; exit 1; fi
+    # Check temp dir arg
+    if ! [ -z "$4" ]; then TMP_DIR="$4"; else yell "ERROR:$FN:No temporary working dir set."; exit 1; fi
+    # Set command strings
+    if ! [ -z "$5" ]; then CMD1="$5"; else CMD1="tee /dev/null "; fi # command string 1
+    if ! [ -z "$6" ]; then CMD2="$6"; else CMD2="tee /dev/null "; fi # command string 2
+    if ! [ -z "$7" ]; then CMD3="$7"; else CMD3="tee /dev/null "; fi # command string 3
+    if ! [ -z "$8" ]; then CMD4="$8"; else CMD4="tee /dev/null "; fi # command string 4
+
+    # Input command string
+    CMD0="cat \"\$1\""
+    
+    # # Debug
+    # yell "DEBUG:STATUS:$FN:CMD0:$CMD0"
+    # yell "DEBUG:STATUS:$FN:CMD1:$CMD1"
+    # yell "DEBUG:STATUS:$FN:CMD2:$CMD2"
+    # yell "DEBUG:STATUS:$FN:CMD3:$CMD3"
+    # yell "DEBUG:STATUS:$FN:CMD4:$CMD4"
+    # yell "DEBUG:STATUS:$FN:FILENAME:$FILENAME"
+    # yell "DEBUG:STATUS:$FN:TAR_PATH:$TAR_PATH"
+    # yell "DEBUG:STATUS:$FN:TMP_DIR:$TMP_DIR"
+    
+    # Write to temporary working dir
+    eval "$CMD0 | $CMD1 | $CMD2 | $CMD3 | $CMD4" > "$TMP_DIR"/"$FILENAME";
+
+    # Append to tar
+    try tar --append --directory="$TMP_DIR" --file="$TAR_PATH" "$FILENAME";
+    #yell "DEBUG:STATUS:$FN:Finished appendFileTar()."
+} # Append file to Tar archive
+checkAgePubkey() {
+    # Desc: Checks if string is an age-compatible pubkey
+    # Usage: checkAgePubkey [str pubkey]
+    # Version: 0.1.2
+    # Input: arg1: string
+    # Output: return code 0: string is age-compatible pubkey
+    #         return code 1: string is NOT an age-compatible pubkey
+    #         age stderr (ex: there is stderr if invalid string provided)
+    # Depends: age (v0.1.0-beta2; https://github.com/FiloSottile/age/releases/tag/v1.0.0-beta2 )
+    
+    argPubkey="$1";
+    
+    if echo "test" | age -a -r "$argPubkey" 1>/dev/null; then
+	return 0;
+    else
+	return 1;
+    fi;
+} # Check age pubkey
+validateInput() {
+    # Desc: Validates Input
+    # Usage: validateInput [str input] [str input type]
+    # Version: 0.3.0
+    # Input: arg1: string to validate
+    #        arg2: string specifying input type (ex:"ssh_pubkey")
+    # Output: return code 0: if input string matched specified string type
+    # Depends: bash 5, yell
+
+    # Save function name
+    local FN="${FUNCNAME[0]}";
+
+    # Process arguments
+    argInput="$1";
+    argType="$2";
+    if [[ $# -gt 2 ]]; then yell "ERROR:$0:$FN:Too many arguments."; exit 1; fi;
+
+    # Check for blank
+    if [[ -z "$argInput" ]]; then return 1; fi
+    
+    # Define input types
+    ## ssh_pubkey
+    ### Check for alnum/dash base64 (ex: "ssh-rsa AAAAB3NzaC1yc2EAAA")
+    if [[ "$argType" = "ssh_pubkey" ]]; then
+	if [[ "$argInput" =~ ^[[:alnum:]-]*[\ ]*[[:alnum:]+/=]*$ ]]; then
+	    return 0; fi; fi;
+
+    ## age_pubkey
+    ### Check for age1[:bech32:]
+    if [[ "$argType" = "age_pubkey" ]]; then
+	if [[ "$argInput" =~ ^age1[qpzry9x8gf2tvdw0s3jn54khce6mua7l]*$ ]]; then
+	    return 0; fi; fi
+
+    ## integer
+    if [[ "$argType" = "integer" ]]; then
+	if [[ "$argInput" =~ ^[[:digit:]]*$ ]]; then
+	    return 0; fi; fi;
+
+    ## time element (year, month, week, day, hour, minute, second)
+    if [[ "$argType" = "time_element" ]]; then
+	if [[ "$argInput" = "year" ]] || \
+	       [[ "$argInput" = "month" ]] || \
+	       [[ "$argInput" = "week" ]] || \
+	       [[ "$argInput" = "day" ]] || \
+	       [[ "$argInput" = "hour" ]] || \
+	       [[ "$argInput" = "minute" ]] || \
+	       [[ "$argInput" = "second" ]]; then
+	    return 0; fi; fi;
+    
+    # Return error if no condition matched.
+    return 1;
+} # Validates strings
+timeEpochNS() {
+    # Desc: Get epoch nanoseconds
+    # Usage: timeEpochNS
+    # Version 0.2.2
+    # Input: arg1: 'date'-parsable timestamp string (optional)
+    # Output: Nanoseconds since 1970-01-01
+    # Depends: date 8, yell()
+    # Ref/Attrib: Force base 10 Bash arith with '10#'. https://stackoverflow.com/a/24777667
+    local TIME_CURRENT TIME_INPUT TIME_EPOCH_FLOAT TIME_EPOCH_NSFRAC
+    local TIME_EPOCH_NS
+
+    argTime="$1";
+
+    # Get Current Time
+    TIME_CURRENT="$(date --iso-8601=ns)"; # Produce `date`-parsable current timestamp with resolution of 1 nanosecond.
+
+    # Decide to parse current or supplied time
+    ## Check if time argument empty
+    if [[ -z "$argTime" ]]; then
+	## T: Time argument empty, use current time
+	TIME_INPUT="$TIME_CURRENT";
+    else
+	## F: Time argument exists, validate time
+	if date --date="$argTime" 1>/dev/null 2>&1; then
+	    ### T: Time argument is valid; use it
+	    TIME_INPUT="$argTime";
+	else
+	    ### F: Time argument not valid; exit
+	    yell "ERROR:Invalid time argument supplied. Exiting."; exit 1;
+	fi;
+    fi;
+    # Construct and deliver nanoseconds since 1970-01-01    
+    TIME_EPOCH_FLOAT="$(date --date="$TIME_INPUT" +%s.%N)"; # Save ssss.NNNNNNNNN
+    TIME_EPOCH_INT="$(echo "$TIME_EPOCH_FLOAT" | cut -d. -f1)"; # Get ssss
+    TIME_EPOCH_NSFRAC="$(echo "$TIME_EPOCH_FLOAT" | cut -d. -f2)"; # Get NNNNNNNNN
+    TIME_EPOCH_NS="$(( (10#"$TIME_EPOCH_INT" * 10**9) + (10#"$TIME_EPOCH_NSFRAC") ))";
+    echo "$TIME_EPOCH_NS";
+} # Nanoseconds since 1970-01-01
+magicBufferSleepPID() {
+    # Desc: Compensates for lag so buffer rounds start every BUFFER_TTL seconds
+    # Input: vars: BUFFER_TTL, errResetx10e3, K_P, T_I, T_D
+    # # Input: array: errorHistory
+    # Output: vars: BUFFER_TTL_ADJ_FLOAT
+    # Re/Attrib: https://en.wikipedia.org/wiki/PID_controller#Standard_versus_parallel_(ideal)_form
+    local BUFFER_TTL_NS
+    local timeBufferStartNS timeBufferStartNSExp errNS errNSx10e3
+    local errResetx10e3 errRatex10e3 ADJ BUFFER_TTL_ADJ_NS BUFFER_TTL_ADJ_INT
+    local BUFFER_TTL_ADJ_FLOATFRAC
+    # local errorHistorySize
+    
+    # ## Define errorHistorySize
+    # errorHistorySize=100;
+    ## Define BUFFER_TTL in nanoseconds
+    BUFFER_TTL_NS=$((BUFFER_TTL * 10**9)) && vbm "BUFFER_TTL_NS:$BUFFER_TTL_NS";
+    
+    # Calculate Error, errNS, in nanoseconds
+    ## Get current time
+    timeBufferStartNS="$(timeEpochNS)" && vbm "timeBufferStartNS:$timeBufferStartNS";
+    ## Calculate expected time (from start time, current buffer round number, nominal BUFFER_TTL)
+    timeBufferStartNSExp="$(( (timeBufferFirstNS) + (BUFFER_TTL_NS * bufferRound) ))" && vbm "timeBufferStartNSExp:$timeBufferStartNSExp";
+    ## Calculate error (diff between timeBufferStartNSExp and timeBufferStartNS; usually negative)
+    errNS="$(( timeBufferStartNSExp - timeBufferStartNS ))" && vbm "errNS:$errNS";
+    errNSx10e3="$((errNS*10**3))" && vbm "errNSx10e3:$errNSx10e3";
+    # ## Append error to errorHistory
+    # errorHistory+=("errNS");
+    # ### Trim errorHistory array if over errorHistorySize
+    # while [[ "${#errorHistory[@]}" -gt "errorHistorySize" ]]; then do
+    # 	unset "errorHistory[0]"; # remove oldest entry, creating sparse array
+    # 	errorHistory=("${errorHistory[@]}"); # reindex sparse array
+    # 	vbm "STATUS:Trimmed errorHistory array. Entry count:${#errorHistory[@]}";
+    # done;
+
+    # Calculate errReset in nanoseconds^2
+    ## errReset = int(errHistory(t),wrt(delta_BUFFER_TTL))
+    ## Integrate errorHistory with respect to time
+    # for value in "${errorHistory[@]}"; do
+    # 	errReset=$(( errReset + ( value*BUFFER_TTL_NS ) ));
+    # done;
+    errResetx10e3="$(( ( errResetx10e3 + ( errNS * BUFFER_TTL_NS ) )*10**3 ))" && vbm "errResetx10e3:$errResetx10e3";
+
+    # Calculate errRate in nanoseconds per 1000 nanoseconds
+    errRatex10e3="$(( ( errNSx10e3 ) / BUFFER_TTL_NS ))" && vbm "errRatex10e3:$errRatex10e3";
+    
+    # Calculate PID control signal
+    ## ADJ = K_P * (errNS + errReset/T_I + errRate*T_D)
+    ADJ="$((K_P*(errNSx10e3 + (errResetx10e3/T_I) + (errRatex10e3*T_D) )/10**3))" && vbm "ADJ:$ADJ";
 
-	# Append location log until midnight.
-	timeout "$SECONDS_UNTIL_NEXT_MIDNIGHT""s" gpspipe -r 1>> "$DIROUTN"/"$FILEOUTN" 2>>/dev/null ; # log raw nmea data
+    # Calculate BUFFER_TTL_ADJ_FLOAT from ADJ (ns)
+    ## Calculate BUFFER_TTL_ADJ in nanoseconds (BUFFER_TTL_ADJ_NS = BUFFER_TTL_NS + ADJ)
+    BUFFER_TTL_ADJ_NS="$((BUFFER_TTL_NS + ADJ))" && vbm "BUFFER_TTL_ADJ_NS:$BUFFER_TTL_ADJ_NS";
+    ## Calculate integer seconds
+    BUFFER_TTL_ADJ_INT="$((BUFFER_TTL_ADJ_NS/(10**9)))" && vbm "BUFFER_TTL_ADJ_INT:$BUFFER_TTL_ADJ_INT";
+    ## Calculate nanosecond remainder
+    BUFFER_TTL_ADJ_FLOATFRAC="$((BUFFER_TTL_NS - (BUFFER_TTL_ADJ_INT*(10**9)) ))" && vbm "BUFFER_TTL_ADJ_FLOATFRAC:$BUFFER_TTL_ADJ_FLOATFRAC";
+    ## Form float BUFFER_TTL_ADJ_FLOAT
+    BUFFER_TTL_ADJ_FLOAT="$BUFFER_TTL_ADJ_INT"."$BUFFER_TTL_ADJ_FLOATFRAC" && vbm "BUFFER_TTL_ADJ_FLOAT:$BUFFER_TTL_ADJ_FLOAT";
+    vbm "STATUS:Calculated adjusted BUFFER_TTL (seconds):$BUFFER_TTL_ADJ_FLOAT";
+    sleep 1 # Debug
+} # Calc BUFFER_TTL_ADJ_FLOAT so buffer starts every BUFFER_TTL seconds
+magicWriteVersion() {
+    # Desc: Appends time-stamped VERSION to PATHOUT_TAR
+    # Usage: magicWriteVersion
+    # Version: 0.1.0
+    # Input: CONTENT_VERSION, FILEOUT_VERSION, PATHOUT_TAR, DIR_TMP
+    # Input: SCRIPT_VERSION, SCRIPT_URL, AGE_VERSION, AGE_URL, SCRIPT_HOSTNAME
+    # Output: appends tar PATHOUT_TAR
+    # Depends: dateTimeShort, appendArgTar
+    local CONTENT_VERSION pubKeyIndex
+    
+    # Set VERSION file name
+    FILEOUT_VERSION="$(dateTimeShort)..VERSION";
+
+    # Gather VERSION data in CONTENT_VERSION
+    CONTENT_VERSION="SCRIPT_VERSION=$SCRIPT_VERSION";
+    #CONTENT_VERSION="$CONTENT_VERSION""\\n";
+    CONTENT_VERSION="$CONTENT_VERSION""\\n""SCRIPT_NAME=$SCRIPT_NAME";
+    CONTENT_VERSION="$CONTENT_VERSION""\\n""SCRIPT_URL=$SCRIPT_URL";
+    CONTENT_VERSION="$CONTENT_VERSION""\\n""AGE_VERSION=$AGE_VERSION";
+    CONTENT_VERSION="$CONTENT_VERSION""\\n""AGE_URL=$AGE_URL";
+    CONTENT_VERSION="$CONTENT_VERSION""\\n""DATE=$(date --iso-8601=seconds)";
+    CONTENT_VERSION="$CONTENT_VERSION""\\n""HOSTNAME=$SCRIPT_HOSTNAME";
+    ## Add list of recipient pubkeys
+    for pubkey in "${recPubKeysValid[@]}"; do
+	((pubKeyIndex++))
+	CONTENT_VERSION="$CONTENT_VERSION""\\n""PUBKEY_$pubKeyIndex=$pubkey";
     done
+    ## Process newline escapes
+    CONTENT_VERSION="$(echo -e "$CONTENT_VERSION")"
+
+    # Write CONTENT_VERSION as file FILEOUT_VERSION and write-append to PATHOUT_TAR
+    appendArgTar "$CONTENT_VERSION" "$FILEOUT_VERSION" "$PATHOUT_TAR" "$DIR_TMP";
+    
+} # bkgpslog: write version data to PATHOUT_TAR via appendArgTar()
+magicGatherWriteBuffer() {
+    # Desc: bkgpslog-specific meta function for writing data to DIR_TMP then appending each file to PATHOUT_TAR
+    # Inputs: vars: PATHOUT_TAR FILEOUT_{NMEA,GPX,KML} CMD_CONV_{NMEA,GPX,KML} CMD_{COMPRESS,ENCRYPT} DIR_TMP,
+    # Inputs: vars: BUFFER_TTL bufferTTL_STR SCRIPT_HOSTNAME CMD_COMPRESS_SUFFIX CMD_ENCRYPT_SUFFIX
+    # Output: file: (PATHOUT_TAR)
+    # Depends: yell(), try(), vbm(), appendArgTar(), tar 1, sleep 8, checkMakeTar()
+    # Depends: magicWriteVersion(), appendFileTar()
+    local FN
+
+    # Debug:Get function name
+    FN="${FUNCNAME[0]}";
+    
+    # Create buffer file with unique name
+    PATHOUT_BUFFER="$DIR_TMP/buffer$SECONDS";
+    # Fill buffer
+    timeout "$BUFFER_TTL"s gpspipe -r -o "$PATHOUT_BUFFER" ;
+    timeBufferStart="$(dateTimeShort  "$(date --date="$BUFFER_TTL seconds ago")")"; # Note start time
+    vbm "DEBUG:STATUS:$FN:Started magicWriteBuffer().";
+    # Determine file paths (time is start of buffer period)
+    FILEOUT_BASENAME="$timeBufferStart""--""$bufferTTL_STR""..""$SCRIPT_HOSTNAME""_location" && vbm "STATUS:Set FILEOUT_BASENAME to:$FILEOUT_BASENAME";
+    ## Files saved to DIR_TMP
+    FILEOUT_NMEA="$FILEOUT_BASENAME".nmea"$CMD_COMPRESS_SUFFIX""$CMD_ENCRYPT_SUFFIX" && vbm "STATUS:Set FILEOUT_NMEA to:$FILEOUT_NMEA";
+    FILEOUT_GPX="$FILEOUT_BASENAME".gpx"$CMD_COMPRESS_SUFFIX""$CMD_ENCRYPT_SUFFIX" && vbm "STATUS:Set FILEOUT_GPX to:$FILEOUT_GPX";
+    FILEOUT_KML="$FILEOUT_BASENAME".kml"$CMD_COMPRESS_SUFFIX""$CMD_ENCRYPT_SUFFIX" && vbm "STATUS:Set FILEOUT_KML to:$FILEOUT_KML";
+    PATHOUT_NMEA="$DIR_TMP"/"$FILEOUT_NMEA" && vbm "STATUS:Set PATHOUT_NMEA to:$PATHOUT_NMEA";
+    PATHOUT_GPX="$DIR_TMP"/"$FILEOUT_GPX" && vbm "STATUS:Set PATHOUT_GPX to:$PATHOUT_GPX";
+    PATHOUT_KML="$DIR_TMP"/"$FILEOUT_KML" && vbm "STATUS:Set PATHOUT_KML to:$PATHOUT_KML";
+    ## Files saved to disk (DIR_OUT)
+    ### one file per day (Ex: "20200731..hostname_location.[.gpx.gz].tar")
+    PATHOUT_TAR="$DIR_OUT"/"$(dateShort "$(date --date="$BUFFER_TTL seconds ago")")".."$SCRIPT_HOSTNAME""_location""$CMD_COMPRESS_SUFFIX""$CMD_ENCRYPT_SUFFIX".tar && \
+	vbm "STATUS:Set PATHOUT_TAR to:$PATHOUT_TAR";
+    # DEBUG: check vars
+    vbm "STATUS:DIR_TMP     :$DIR_TMP";
+    vbm "STATUS:PATHOUT_TAR :$PATHOUT_TAR";
+    vbm "STATUS:PATHOUT_NMEA:$PATHOUT_NMEA";
+    vbm "STATUS:PATHOUT_GPX:$PATHOUT_GPX";
+    vbm "STATUS:PATHOUT_KML:$PATHOUT_KML";
+    
+    
+    # Validate PATHOUT_TAR as tar.
+    checkMakeTar "$PATHOUT_TAR";
+    ## Add VERSION file if checkMakeTar had to create a tar (exited 1) or replace one (exited 2)
+    if [[ $? -eq 1 ]] || [[ $? -eq 2 ]]; then magicWriteVersion; fi
+
+    # Write bufferBash to PATHOUT_TAR
+    wait; # Wait to avoid collision with older magicWriteBuffer() instances (see https://www.tldp.org/LDP/abs/html/x9644.html )
+    appendFileTar "$PATHOUT_BUFFER" "$FILEOUT_NMEA" "$PATHOUT_TAR" "$DIR_TMP" "$CMD_CONV_NMEA" "$CMD_COMPRESS" "$CMD_ENCRYPT"; # Write NMEA data
+    appendFileTar "$PATHOUT_BUFFER" "$FILEOUT_GPX" "$PATHOUT_TAR" "$DIR_TMP" "$CMD_CONV_GPX" "$CMD_COMPRESS" "$CMD_ENCRYPT"; # Write GPX file
+    appendFileTar "$PATHOUT_BUFFER" "$FILEOUT_KML" "$PATHOUT_TAR" "$DIR_TMP" "$CMD_CONV_KML" "$CMD_COMPRESS" "$CMD_ENCRYPT"; # Write KML file
+
+    # Remove secured chunks from DIR_TMP
+    rm "$PATHOUT_BUFFER" "$PATHOUT_NMEA" "$PATHOUT_GPX" "$PATHOUT_KML";
+    vbm "DEBUG:STATUS:$FN:Finished magicWriteBuffer().";
+} # write buffer to disk
+magicParseRecipientDir() {
+    # Desc: Updates recPubKeysValid with pubkeys in dir specified by '-R' option ("recipient directory")
+    # Inputs:  vars: OPTION_RECDIR, argRecDir, OPTION_ENCRYPT
+    #          arry: recPubKeysValid
+    # Outputs: arry: recPubKeysValid
+    # Depends: processArguments,
+    local recFileLine updateRecipients recipientDir
+    declare -a candRecPubKeysValid
+
+    # Check that '-e' and '-R' set
+    if [[ "$OPTION_ENCRYPT" = "true" ]] && [[ "$OPTION_RECDIR" = "true" ]]; then
+	### Check that argRecDir is a directory.
+	if [[ -d "$argRecDir" ]]; then
+	    recipientDir="$argRecDir" && vbm "STATUS:Recipient watch directory detected:\"$recipientDir\"";
+	    #### Initialize variable indicating outcome of pubkey review
+	    unset updateRecipients
+	    #### Add existing recipients
+	    candRecPubKeysValid=("${recPubKeysValidStatic[@]}");
+	    #### Parse files in recipientDir
+	    for file in "$recipientDir"/*; do
+		##### Read first line of each file
+		recFileLine="$(head -n1 "$file")" && vbm "STATUS:Checking if pubkey:\"$recFileLine\"";
+		##### check if first line is a valid pubkey
+		if checkAgePubkey "$recFileLine" && \
+			( validateInput "$recFileLine" "ssh_pubkey" || validateInput "$recFileLine" "age_pubkey"); then
+		    ###### T: add candidate pubkey to candRecPubKeysValid
+		    candRecPubKeysValid+=("$recFileLine") && vbm "STATUS:RecDir pubkey is valid pubkey:\"$recFileLine\"";
+		else
+		    ###### F: throw warning;
+		    yell "ERROR:Invalid recipient file detected. Not modifying recipient list."
+		    updateRecipients="false";
+		fi;
+	    done
+	    #### Write updated recPubKeysValid array to recPubKeysValid if no failure detected
+	    if ! [[ "$updateRecipients" = "false" ]]; then
+		recPubKeysValid=("${candRecPubKeysValid[@]}") && vbm "STATUS:Wrote candRecPubkeysValid to recPubKeysValid:\"${recPubKeysValid[*]}\"";
+	    fi;
+	else
+	    yell "ERROR:$0:Recipient directory $argRecDir does not exist. Exiting."; exit 1;
+	fi;
+    fi;
+    # Handle case if '-R' set but '-e' not set
+    if [[ ! "$OPTION_ENCRYPT" = "true" ]] && [[ "$OPTION_RECDIR" = "true" ]]; then
+	yell "ERROR: \\'-R\\' is set but \\'-e\\' is not set."; fi;
+} # Update recPubKeysValid with argRecDir
+magicParseRecipientArgs() {
+    # Desc: Parses recipient arguments specified by '-r' option
+    # Input:  vars: OPTION_ENCRYPT from processArguments()
+    #         arry: argRecPubKeys from processArguments()
+    # Output: vars: CMD_ENCRYPT, CMD_ENCRYPT_SUFFIX
+    #         arry: recPubKeysValid, recPubKeysValidStatic
+    # Depends: checkapp(), checkAgePubkey(), validateInput(), processArguments()
+    local recipients
+
+    # Check if encryption option active.
+    if [[ "$OPTION_ENCRYPT" = "true" ]] && [[ "$OPTION_RECIPIENTS" = "true" ]]; then 
+	if checkapp age; then # Check that age is available.
+	    for pubkey in "${argRecPubKeys[@]}"; do # Validate recipient pubkey strings by forming test message
+		vbm "DEBUG:Testing pubkey string:$pubkey";
+		if checkAgePubkey "$pubkey" && \
+			( validateInput "$pubkey" "ssh_pubkey" || validateInput "$pubkey" "age_pubkey"); then
+		    #### Form age recipient string
+		    recipients="$recipients""-r '$pubkey' ";
+		    vbm "STATUS:Added pubkey for forming age recipient string:""$pubkey";
+		    vbm "DEBUG:recipients:""$recipients";
+		    #### Add validated pubkey to recPubKeysValid array
+		    recPubKeysValid+=("$pubkey") && vbm "DEBUG:recPubkeysValid:pubkey added:$pubkey";
+		else
+		    yell "ERROR:Exit code ""$?"". Invalid recipient pubkey string. Exiting."; exit 1;
+		fi;
+	    done
+	    vbm "DEBUG:Finished processing argRecPubKeys array";
+	    vbm "STATUS:Array of validated pubkeys:${recPubKeysValid[*]}";
+	    recPubKeysValidStatic=("${recPubKeysValid[@]}"); # Save static image of pubkeys validated by this function
+
+	    ##  Form age command string
+	    CMD_ENCRYPT="age ""$recipients " && vbm "CMD_ENCRYPT:$CMD_ENCRYPT";
+	    CMD_ENCRYPT_SUFFIX=".age" && vbm "CMD_ENCRYPT_SUFFIX:$CMD_ENCRYPT_SUFFIX";
+	else
+	    yell "ERROR:Encryption enabled but \"age\" not found. Exiting."; exit 1;
+	fi;
+    else
+	CMD_ENCRYPT="tee /dev/null " && vbm "CMD_ENCRYPT:$CMD_ENCRYPT";
+	CMD_ENCRYPT_SUFFIX="" && vbm "CMD_ENCRYPT_SUFFIX:$CMD_ENCRYPT_SUFFIX";
+	vbm "DEBUG:Encryption not enabled."
+    fi;
+    # Catch case if '-e' is set but '-r' or '-R' is not
+    if [[ "$OPTION_ENCRYPT" = "true" ]] && [[ ! "$OPTION_RECIPIENTS" = "true" ]]; then
+	yell "ERROR:\\'-e\\' set but no \\'-r\\' or \\'-R\\' set."; exit 1; fi;
+    # Catch case if '-r' or '-R' set but '-e' is not
+    if [[ ! "$OPTION_ENCRYPT" = "true" ]] && [[ "$OPTION_RECIPIENTS" = "true" ]]; then
+	yell "ERROR:\\'-r\\' or \\'-R\\' set but \\'-e\\' is not set."; exit 1; fi; 
+} # Populate recPubKeysValid with argRecPubKeys; form encryption cmd string and filename suffix
+magicParseCompressionArg() {
+    # Desc: Parses compression arguments specified by '-c' option
+    # Input:  vars: OPTION_COMPRESS
+    # Output: CMD_COMPRESS, CMD_COMPRESS_SUFFIX
+    # Depends: checkapp(), vbm(), gzip, 
+    if [[ "$OPTION_COMPRESS" = "true" ]]; then # Check if compression option active
+	if checkapp gzip; then # Check if gzip available
+	    CMD_COMPRESS="gzip " && vbm "CMD_COMPRESS:$CMD_COMPRESS";
+	    CMD_COMPRESS_SUFFIX=".gz" && vbm "CMD_COMPRESS_SUFFIX:$CMD_COMPRESS_SUFFIX";
+	else
+	    yell "ERROR:Compression enabled but \"gzip\" not found. Exiting."; exit 1;
+	fi
+    else
+	CMD_COMPRESS="tee /dev/null " && vbm "CMD_COMPRESS:$CMD_COMPRESS";
+	CMD_COMPRESS_SUFFIX="" && vbm "CMD_COMPRESS_SUFFIX:$CMD_COMPRESS_SUFFIX";
+	vbm "DEBUG:Compression not enabled.";
+    fi    
+} # Form compression cmd string and filename suffix
+magicInitWorkingDir() {
+    # Desc: Determine temporary working directory from defaults or user input
+    # Usage: magicInitWorkignDir
+    # Input:  vars: OPTION_TEMPDIR, argTempDirPriority, DIR_TMP_DEFAULT
+    # Input:  vars: SCRIPT_TIME_START
+    # Output: vars: DIR_TMP
+    # Depends: processArguments(), vbm(), yell()
+    # Parse '-t' option (user-specified temporary working dir)
+    ## Set DIR_TMP_PARENT to user-specified value if specified
+    local DIR_TMP_PARENT
     
-    #gpspipe -r -d -l -o "$DIROUT1"/"$FILEOUT1" ;
+    if [[ "$OPTION_TMPDIR" = "true" ]]; then
+	if [[ -d "$argTempDirPriority" ]]; then
+	    DIR_TMP_PARENT="$argTempDirPriority"; 
+	else
+	    yell "WARNING:Specified temporary working directory not valid:$argTempDirPriority";
+	    exit 1; # Exit since user requires a specific temp dir and it is not available.
+	fi;
+    else
+    ## Set DIR_TMP_PARENT to default or fallback otherwise
+	if [[ -d "$DIR_TMP_DEFAULT" ]]; then
+	    DIR_TMP_PARENT="$DIR_TMP_DEFAULT";
+	elif [[ -d /tmp ]]; then
+	    yell "WARNING:$DIR_TMP_DEFAULT not available. Falling back to /tmp .";
+	    DIR_TMP_PARENT="/tmp";
+	else
+	    yell "ERROR:No valid working directory available. Exiting.";
+	    exit 1;
+	fi
+    fi;
+    ## Set DIR_TMP using DIR_TMP_PARENT and nonce (SCRIPT_TIME_START)
+    DIR_TMP="$DIR_TMP_PARENT"/"$SCRIPT_TIME_START""..bkgpslog" && vbm "DEBUG:Set DIR_TMP to:$DIR_TMP"; # Note: removed at end of main().    
+} # Sets working dir
+magicParseCustomTTL() {
+    # Desc: Set user-specified TTLs for buffer and script
+    # Input: vars: argCustomBufferTTL (integer), argCustomScriptTTL_TE (string)
+    # Input: vars: OPTION_CUSTOM_BUFFERTTL, OPTION_CUSTOM_SCRIPTTTL
+    # Input: vars: BUFFER_TTL (integer), SCRIPT_TTL_TE (string)
+    # Output: BUFFER_TTL (integer), SCRIPT_TTL_TE (string)
+    # Depends validateInput(), showUsage(), yell
+
+    # React to '-b, --buffer-ttl' option
+    if [[ "$OPTION_CUSTOM_BUFFERTTL" = "true" ]]; then
+	## T: Check if argCustomBufferTTL is an integer
+	if validateInput "$argCustomBufferTTL" "integer"; then
+	    ### T: argCustomBufferTTL is an integer
+	    BUFFER_TTL="$argCustomBufferTTL";
+	else
+	    ### F: argcustomBufferTTL is not an integer
+	    yell "ERROR:Invalid integer argument for custom buffer time-to-live."; showUsage; exit 1;
+	fi;
+	## F: do not change BUFFER_TTL
+    fi;
     
-else
-    echo "$SCRIPT_TIME_SHORT"">gpspipe or $DIROUT1 not found." >> ~/"$SCRIPT_DATE_SHORT"..error.log ;
-fi
+    # React to '-B, --script-ttl' option
+    if [[ "$OPTION_CUSTOM_SCRIPTTTL_TE" = "true" ]]; then
+	## T: Check if argCustomScriptTTL is a time element (ex: "day", "hour")
+	if validateInput "$argCustomScriptTTL" "time_element"; then
+	    ### T: argCustomScriptTTL is a time element
+	    SCRIPT_TTL_TE="$argCustomScriptTTL";
+	else
+	    ### F: argcustomScriptTTL is not a time element
+	    yell "ERROR:Invalid time element argument for custom script time-to-live."; showUsage; exit 1;
+	fi;
+	## F: do not change SCRIPT_TTL_TE
+    fi;    
+} # Sets custom script or buffer TTL if specified
+
+
+main() {
+    # Process arguments
+    processArguments "$@";
+    ## Act upon arguments
+    ### Determine working directory
+    magicInitWorkingDir; # Sets DIR_TMP from argTempDirPriority
+    ### Set output encryption and compression option strings
+    #### React to "-r" ("encryption recipients") option
+    magicParseRecipientArgs; # Updates recPubKeysValid, CMD_ENCRYPT[_SUFFIX] from argRecPubKeys
+    #### React to "-c" ("compression") option
+    magicParseCompressionArg; # Updates CMD_COMPRESS[_SUFFIX]
+    #### React to "-R" ("recipient directory") option
+    magicParseRecipientDir; # Updates recPubKeysValid
+    #### React to custom buffer and script TTL options ("-b", "-B")
+    magicParseCustomTTL; # Sets custom SCRIPT_TTL_TE and/or BUFFER_TTL if specified
+
+    # Check that critical apps and dirs are available, display missing ones.
+    if ! checkapp gpspipe tar && ! checkdir "$DIR_OUT" "DIR_TMP"; then
+	yell "ERROR:Critical components missing.";
+	displayMissing; yell "Exiting."; exit 1; fi
+
+    # Set script lifespan (SCRIPT_TTL from SCRIPT_TTL_TE)
+    magicSetScriptTTL "$SCRIPT_TTL_TE";
+    ## Note: SCRIPT_TTL_TE is time element string (ex: "day") while SCRIPT_TTL is integer seconds
+
+    # File name substring (ISO-8601 duration from BUFFER_TTL)
+    bufferTTL_STR="$(timeDuration "$BUFFER_TTL")";
+
+    # Init temp working dir
+    try mkdir "$DIR_TMP" && vbm "DEBUG:Working dir creatd at:$DIR_TMP";
+
+    # Initialize 'tar' archive
+    ## Define output tar path (note: each day gets *one* tar file (Ex: "20200731..hostname_location.[.gpx.gz].tar"))
+    PATHOUT_TAR="$DIR_OUT"/"$(dateShort)".."$SCRIPT_HOSTNAME""_location""$CMD_COMPRESS_SUFFIX""$CMD_ENCRYPT_SUFFIX".tar && \
+	vbm "STATUS:Set PATHOUT_TAR to:$PATHOUT_TAR";
+    ## Check that PATHOUT_TAR is a tar. Rename old and create empty one otherwise.
+    checkMakeTar "$PATHOUT_TAR" && vbm "DEBUG:Confirmed or Created to be a tar:$PATHOUT_TAR";
+    ## Append VERSION file to PATHOUT_TAR
+    magicWriteVersion;
+
+    # Define GPS conversion commands
+    CMD_CONV_NMEA="tee /dev/null " && vbm "STATUS:Set CMD_CONV_NMEA to:$CMD_CONV_NMEA"; # tee as passthrough
+    CMD_CONV_GPX="gpsbabel -i nmea -f - -o gpx -F - " && vbm "STATUS:Set CMD_CONV_GPX to:$CMD_CONV_GPX"; # convert NMEA to GPX
+    CMD_CONV_KML="gpsbabel -i nmea -f - -o kml -F - " && vbm "STATUS:Set CMD_CONV_KML to:$CMD_CONV_KML"; # convert NMEA to KML
+
+    # MAIN LOOP:Record gps data until script lifespan ends
+    timeBufferFirstNS="$(timeEpochNS)"; bufferRound=0
+    while [[ "$SECONDS" -lt "$SCRIPT_TTL" ]]; do
+	magicParseRecipientDir;
+	magicGatherWriteBuffer &
+	magicBufferSleepPID; # Calculates BUFFER_TTL_ADJ from BUFFER_TTL given buffer expected start time vs. actual
+	sleep "$BUFFER_TTL_ADJ_FLOAT";
+	((bufferRound++));
+    done    
+
+    # Cleanup
+    ## Remove DIR_TMP
+    try rm -r "$DIR_TMP";
+
+    vbm "STATUS:Main function finished.";
+} # Main function.
+#===END Declare local script functions===
+#==END Define script parameters==
+
+
+#==BEGIN Perform work and exit==
+main "$@" # Run main function.
+exit 0;
+#==END Perform work and exit==