[BK-2020-03.git] / unitproc / bktemplate

#!/bin/bash

# Author: Steven Baltakatei Sandoval
# Description: Template for bash scripts.
# Note: Use hide-show-block function to aid readability. (ex: https://www.emacswiki.org/emacs/HideShow ).

#== Variable Initialization ==

#== Global constants ==
SCRIPT_TTL=10                   # Limit script life to this in seconds.
PATH="/usr/local/bin/:$PATH"    # Add user binary executable directory to PATH.
PATH="/opt/bktei:$PATH"         # Add 'optional' executable directory to PATH.
SCRIPT_HOSTNAME=$(hostname)     # Save hostname of system running this script.
SCRIPT_VERSION="bktemplate.sh 0.0.0" # Define version of script. Used by function 'showVersion'.
SCRIPT_TIME_SHORT="$(date +%Y%m%dT%H%M%S%z)" # Save current date & time in ISO-8601 format (YYYYmmddTHHMMSS+zzzz).
SCRIPT_DATE_SHORT="$(date +%Y%m%d)"          # Save current date in ISO-8601 format.

#==BEGIN Define script parameters
declare -Ag appRollCall # Associative array for storing app status (function checkapp())
declare -Ag fileRollCall # Associative array for storing file status (function checkfile())
#==END Define script parameters

#== Function Definitions ==


yell() { echo "$0: $*" >&2; } # Yell, Die, Try Three-Fingered Claw technique; # Ref/Attrib: https://stackoverflow.com/a/25515370
die() { yell "$*"; exit 111; }
try() { "$@" || die "cannot $*"; }

echoerr() {
    # Usage: echo [ arguments ]
    # Description: Prints provided arguments to stderr.
    # Input: unspecified
    # Output: stderr
    # Script function dependencies: none
    # External function dependencies: echo
    # Last modified: 2020-04-11T21:16Z
    # Last modified by: Steven Baltakatei Sandoval
    # License: GPLv3+
    # Ref./Attrib:
    #  [1]: # Roth, James (2010-06-07). ["How to print text to stderr instead of stdout"](https://stackoverflow.com/a/2990533). Licensed CC BY-SA 4.0.
    
    echo "$@" 1>&2; # Define stderr echo function. See [1].
    return 0; # Function finished.
} # Define stderr message function.
vbm() {
    # Usage: vbm "DEBUG:verbose message here"
    # Description: Prints verbose message ("vbm") to stderr if OPTION_VERBOSE is set to "true".
    # Input:
    #   - OPTION_VERBOSE  variable set by processArguments function. (ex: "true", "false")
    #   - "$@"            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.
run() {
    # Usage: run [cmd]
    # Description: Runs command; reports success if command exit code 0; exits otherwise.
    # Input: none
    # Output: stdout
    # Script function dependencies: none
    # Last modified: 2020-06-19T22:09Z
    # Last modified by: Steven Baltakatei Sandoval
    # License: GPLv3+
    # Ref.Attrib: https://stackoverflow.com/a/18880585
    cmd_output=$(eval $1)
    return_value=$?
    if [ $return_value != 0 ]; then
	echo "Command $1 failed";
	exit -1;
    else
	echo "output: $cmd_output";
	echo "Command succeeded.";
    fi
    return $return_value
} # 
showUsage() {
    # Usage: showUsage
    # Description: Displays script usage information.
    # Input: none
    # Output: stderr
    # Script function dependencies: echoerr
    # External dependencies: bash (5.0.3), echo
    # Last modified: 2020-05-04T16:11Z
    # Last modified by: Steven Baltakatei Sandoval
    # License: GPLv3+
    # Ref./Attrib.:
    
    echoerr "USAGE:"
    echoerr "    bktemplate.sh [ 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-file [ file ]"
    echoerr "            Specify output file."
    echoerr
    echoerr "    -i, --input-file [ file ]"
    echoerr "            Specify input file."
    echoerr
    echoerr "    -o, --output-dir [ directory ]"
    echoerr "            Specify output directory."
    echoerr
    echoerr "    -i, --input-dir [ directory ]"
    echoerr "            Specify input directory."
    echoerr

    # End function
    return 0; # Function finished.
} # Display information on how to use this script.
showVersion() {
    # Usage: showVersion
    # Descriptoin: Displays script version and license information.
    # Input: unspecified
    # 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:

    # Initialize function
    vbm "DEBUG:showVersion function called."

    # Perform work
    OUTPUT="$SCRIPT_VERSION"

    # Display results
    echoerr "$OUTPUT";

    # End function
    vbm "DEBUG:showVersion function ended."
    return 0; # Function finished.
} # Display script version.
processArguments() {
    # Usage: processArguments "$@"
    # Description: Processes provided arguments in order to set script option variables useful for
    #   changing how other functions behave. For example, it may:
    #   1. Activate verbose mode
    # Input: "$@"          (list of arguments provided to the function)
    # Output: Sets following variables used by other functions:
    #   OPTION_VERBOSE     Indicates verbose mode enable status.  (ex: "true", "false")
    #   DIROUT1            Path to output directory.
    #   FILEOUT1           Path to output file.
    #   DIRIN1             Path to input directory.
    #   FILEIN1            Path to input file.
    #   OPTION_FILEOUT1_OVERWRITE Indicates whether file FILEOUT1 should be overwritten (ex: "true", "false')
    # Script function dependencies:
    #   - echoerr          Displays messages to stderr.
    #   - vbm              Displays messsages to stderr if OPTION_VERBOSE set to "true".
    # External dependencies: bash (5.0.3), echo
    # Last modified: 2020-05-04T14:41Z
    # Last modified by: Steven Baltakatei Sandoval
    # License: GPLv3+
    # Ref./Attrib.:
    #  [1]: Marco Aurelio (2014-05-08). "echo that outputs to stderr". https://stackoverflow.com/a/23550347

    # Initialize function
    #vbm "DEBUG:processArguments function called."

    # Perform work
    while [ ! $# -eq 0 ]; do   # While number of arguments ($#) is not (!) equal to (-eq) zero (0).
	#1>&2 echo "DEBUG:Starting processArguments while loop." # Debug stderr message. See [1].
        #1>&2 echo "DEBUG:Provided arguments are:""$@" # Debug stderr message. See [1].
	case "$1" in
	    -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. See [1].
	    -i | --input-file) # Define input file path
		if [ -f "$2" ]; then # If $2 is file that exists, set FILEIN1 to $2, pop $2.
		    FILEIN1="$2";
		    shift;
		    vbm "DEBUG:Input file FILEIN1 set to:""$2";
		else
		    echoerr "ERROR: Specified input file does not exist:""$2";
		    echoerr "Exiting.";
		    exit 1;
		fi ;; 
	    -I | --input-dir) # Define input directory path
		if [ -d "$2" ]; then # If $2 is dir that exists, set DIRIN1 to $2, pop $2.
		    DIRIN1="$2";
		    shift;
		    vbm "DEBUG:Input directory DIRIN1 set to:""$2";
		else # Display error if $2 is not a valid dir.
		    echoerr "ERROR:Specified input directory does not exist:""$2";
		    echoerr "Exiting.";
		    exit 1;
		fi ;; 
	    -o | --output-file) # Define output file path
		if [ -f "$2" ]; then # If $2 is file that exists, prompt user to continue to overwrite, set FILEOUT1 to $2, pop $2.
		    echoerr "Specified output file $2 already exists. Overwrite? (y/n):"
		    read m; case $m in
				y | Y | yes) OPTION_FILEOUT1_OVERWRITE="true";;
				n | N | no) OPTION_FILEOUT1_OVERWRITE="false";;
				*) echoerr "Invalid selection. Exiting."; exit 1;;
			    esac
		    if [ "$OPTION_FILEOUT1_OVERWRITE" == "true" ]; then
			FILEOUT1="$2";
			shift;
			vbm "DEBUG:Output file FILEOUT1 set to:""$2";
		    else
			echoerr "ERORR:Exiting in order to not overwrite output file:""$FILEOUT1";
			exit 1;
		    fi
		else
		    FILEOUT1="$2";
		    shift;
		    vbm "DEBUG:Output file FILEOUT1 set to:""$2";
		fi ;;
	    -O | --output-dir) # Define output directory path
		if [ -d "$2" ]; then # If $2 is dir that exists, set DIROUT1 to $2, pop $2
		    DIROUT1="$2";
		    shift;
		    vbm "DEBUG:Output directory DIROUT1 set to:""$2";
		else
		    echoerr "ERROR:Specified output directory is not valid:""$2";
		    echoerr "Exiting.";
		    exit 1;
		fi ;; 
	    *) echoerr "ERROR: Unrecognized argument."; exit 1;; # Handle unrecognized options. See [1].
	esac
	shift
    done

    # End function
    vbm "DEBUG:processArguments function ended."
    return  0; # Function finished.
} # Evaluate script options from positional arguments (ex: $1, $2, $3, etc.).
checkExecutables() {
    # Usage: checkExecutables [ command1 ] [ command2 ] [...] [ commandN ]
    # Description: Checks that provided commands exist and displays those that do not exist.
    # Input:
    #   - command names (arguments)
    # Output: commands that don't exist (stderr)
    # Script function dependencies:
    #   - echoerr          for displaying errors via stderr
    #   - processArguments for setting OPTION_VERBOSE
    #   - vbm              for displaying verbose messages if OPTION_VERBOSE is "true"
    # External dependencies: bash (5.0.3), command
    # Last modified: 2020-04-11T23:59Z
    # Last modified by: Steven Baltakatei Sandoval
    # License: GPLv3+
    # Ref./Attrib.:
    #  [1]: SiegeX (2010-12-12). ["Difference between return and exit in Bash functions."](https://stackoverflow.com/a/4419971). Licensed CC BY-SA 4.0.
    #  [2]: Darryl Hein (2009-12-23). ["Add a new element to an array without specifying the index in Bash"](https://stackoverflow.com/a/1951523). Licensed CC BY-SA 4.0.
    #  [3]: kojiro (2012-10-03). ["Convert command line arguments into an array in Bash"](https://stackoverflow.com/a/12711853)
    #  [4]: niieani (2016-01-12). ["How to copy an array in Bash?"](https://stackoverflow.com/a/34733375/10850071). Licensed CC BY-SA 4.0.

    # Initialize function
    vbm "DEBUG:checkExecutables function called."
    declare -a candidateCommandsNames # Initialize array for storing positional arguments provided to this function.
    candidateCommandsNames=("$@") # Save positional arguments to variable as string. See [3].
    vbm "DEBUG:candidateCommandsNames:""$@"
    vbm "DEBUG:candidateCommandsNames[0]:""${candidateCommandsNames[0]}"
    vbm "DEBUG:candidateCommandsNames[1]:""${candidateCommandsNames[1]}"
    vbm "DEBUG:candidateCommandsNames[2]:""${candidateCommandsNames[2]}"
    declare -a outputInvalidCommandsArray # Initialize arary for storing names of invalid commands.
    declare -a outputValidCommandsArray # Initialize array for storing names of valid commands.

    # Perform work
    for candidateCommandName in "${candidateCommandsNames[@]}"; do  # Search through all space-delimited text for valid commands.
	if command -v "$candidateCommandName" 1>/dev/null 2>/dev/null; then # Check if a command is valid or not.
	    outputValidCommandsArray+=("$candidateCommandName") ; # See [2].
	    vbm "DEBUG:Adding $candidateCommandName to outputValidCommandsArray."
	else
	    outputInvalidCommandsArray+=("$candidateCommandName") ; # See [2].
	    vbm "DEBUG:Adding $candidateCommandName to outputInvalidCommandsArray."
	fi
    done

    # Output results
    if [ ${#outputInvalidCommandsArray[@]} -gt 0 ]; then # if number of elements in outputInvalidCommandsArray greater than 0, then display offending commands and exit 1.
	echoerr "ERROR: Invalid commands found:""${outputInvalidCommandsArray[@]}"; # display invalid commands as error
	exit 1; # See [1].
    elif [ ${#outputInvalidCommandsArray[@]} -eq 0 ]; then # if number of elements in outputInvalidCommandsArray equals zero, then return 0.
	vbm "DEBUG: Valid commands are:""${outputValidCommandsArray[@]}"; # display valid commands if verbose mode enabled
	return 0; # See [1].
    else
	echoerr "ERROR: Check outputInvalidCommandsArray.";
    fi

    # End function
    vbm "DEBUG:checkExecutables function ended."
    return 0; # Function finished.
} # Check that certain executables exist.
updateTimeConstants() {
    # Usage: updateTimeConstants
    # Description: Updates time-related variables for use by other scripts.
    # Input: (none)
    # Output: Sets following variables:
    #   TIME_CURRENT       Current time in long ISO-8601 format.  (ex: YYYY-mm-ddTHH:MM:SS+ZZZZ)
    #   TIME_CURRENT_SHORT Current time in short ISO-8601 format. (ex: YYYYmmddTHHMMSS+ZZZZ)
    #   DATE_CURRENT       Current date in ISO-8601 format.       (ex: YYYY-mm-dd)
    #   DATE_CURRENT_SHORT Current date in short ISO-8601 format. (ex: YYYYmmdd)
    #   DATE_TOMORROW      Tomorrow's date in ISO-8601 format.    (ex: YYYY-mm-dd)
    #   TIME_NEXT_MIDNIGHT Time of tomorrow's midnight in long    (ex: YYYY-mm-ddTHH:MM:SS+ZZZZ)
    #                       ISO-861 format.
    #   SEC_TIL_MIDNIGHT   Seconds until next midnight.
    # Script function dependencies:
    #   - echoerr          for displaying errors via stderr
    #   - processArguments for setting OPTION_VERBOSE
    #   - vbm              for displaying verbose messages if OPTION_VERBOSE is "true"
    # External dependencies: bash (5.0.3), date, echo
    # Last modified: 2020-04-11T23:59Z
    # Last modified by: Steven Baltakatei Sandoval
    # License: GPLv3+
    # Ref./Attrib.:

    # Initialize function
    vbm "DEBUG:updateTimeConstants function called."

    # Perform work
    TIME_CURRENT="$(date --iso-8601=seconds)" ;
    TIME_CURRENT_SHORT="$(date -d "$TIME_CURRENT" +%Y%m%dT%H%M%S%z)"
    DATE_CURRENT="$(date -d "$TIME_CURRENT" --iso-8601=date)" ;
    DATE_CURRENT_SHORT="$(date -d "$TIME_CURRENT" +%Y%m%d)" ;
    DATE_TOMORROW="$(date -d "$TIME_CURRENT next day" --iso-8601=date)" ;
    TIME_NEXT_MIDNIGHT="$(date -d "$DATE_TOMORROW" --iso-8601=seconds)" ;
    SECONDS_UNTIL_NEXT_MIDNIGHT="$((  $(date +%s -d "$TIME_NEXT_MIDNIGHT") - $(date +%s -d "$TIME_CURRENT")  ))" ;

    # End function
    vbm "DEBUG:updateTimeConstants function ended."
    return 0; # Function finished.
} # Update time constants
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


#== Main Program Definition ==
main() {
    # Usage: main "$@"    # See [1].
    # Input: unspecified (note: all Global Constants declared at beginning of script assumed to be available)
    #   OPTION_VERBOSE   (used by vbm, set by processArguments)  (ex: "true", "false")
    # Output: unspecified
    # Script function dependencies:
    #   - echoerr          for displaying errors via stderr
    #   - vbm              for displaying verbose messages if OPTION_VERBOSE is "true"
    #   - processArguments for setting OPTION_VERBOSE
    #   - checkExecutables for checking that specified commands are available
    # External dependencies: bash (5.0.3), echo
    # Last modified: 2020-05-04T16:50Z
    # Last modified by: Steven Baltakatei Sandoval
    # License: GPLv3+
    # Ref./Attrib.:
    #  [1]: ErichBSchulz (2011-11-20). [How to correctly pass bash script arguments to functions](https://stackoverflow.com/a/8198970). Licensed CC BY-SA 4.0.

    # Initialize function
    processArguments "$@" # Process arguments.
    vbm "DEBUG:main function called."
    vbm "DEBUG:main function arguments are:""$@"
    checkExecutables "echo" "date" "cut" "awk" # Confirm that executables necessary to run are available. Exit if any fail.

    # Process inputs
    if [ -v FILEIN1 ]; then # VERBOSE: Display contents of FILEIN1 if FILEIN1 has been set.
	vbm "DEBUG:main function detects input file:""$FILEIN1" ;
	vbm "DEBUG:contents of following file is displayed below:""$FILEIN1" ;
	if [ "$OPTION_VERBOSE" == "true" ]; then # display FILEIN1 contents via cat if verbose mode specified
	    echoerr "========""$FILEIN1"" START""========" ;
	    cat "$FILEIN1" 1>&2 ;
	    echoerr "========""$FILEIN1"" END""========" ;
	fi
    fi
    
    # Perform work
    OUTPUT="$OUTPUT""Hello world.\n"
    if [ -v FILEIN1 ]; then
	OUTPUT="$OUTPUT""The b2sum hash of $FILEIN1 is: $(b2sum "$FILEIN1" | awk '{print $1}').\n";
    fi
    OUTPUT="$OUTPUT""The current time is:""$SCRIPT_TIME_SHORT\n"

    # Output results
    echo -e "$OUTPUT"

    if [ -v FILEOUT1 ]; then  # if FILEOUT1 set, write to this file.
	vbm "DEBUG:main function detects output file:""$FILEOUT1" ;
	echo -e "$OUTPUT" > "$FILEOUT1" ;
	vbm "DEBUG:main funtion wrote OUTPUT to:""$FILEOUT1" ;
    elif [ -v DIROUT1 ]; then  # else if DIROUT1 set, set FILEOUT1 to timestamped filename, combine into PATHOUT1, write output to PATHOUT1.
	vbm "DEBUG:main function detects output directory:""$DIROUT1" ;
	FILEOUT1="$SCRIPT_TIME_SHORT"..output
	PATHOUT1="$DIROUT1"/"$FILEOUT1"
	echo -e "$OUTPUT" > $PATHOUT1 ;
	vbm "DEBUG:main function wrote output file to:""$PATHOUT1" ;
    fi

    # End function
    vbm "DEBUG:main function ended."
    return 0; # Function finished.
}

#== Perform work and exit ==
main "$@" # Run main function.
exit 0;
Commit	Line	Data
0d22dfcd SBS	1	#!/bin/bash
0d22dfcd SBS	2
0d22dfcd	3	# Author: Steven Baltakatei Sandoval
fdf917e1	4	# Description: Template for bash scripts.
0d22dfcd SBS	5	# Note: Use hide-show-block function to aid readability. (ex: https://www.emacswiki.org/emacs/HideShow ).
	6
	7	#== Variable Initialization ==
	8
	9	#== Global constants ==
	10	SCRIPT_TTL=10 # Limit script life to this in seconds.
	11	PATH="/usr/local/bin/:$PATH" # Add user binary executable directory to PATH.
	12	PATH="/opt/bktei:$PATH" # Add 'optional' executable directory to PATH.
	13	SCRIPT_HOSTNAME=$(hostname) # Save hostname of system running this script.
	14	SCRIPT_VERSION="bktemplate.sh 0.0.0" # Define version of script. Used by function 'showVersion'.
	15	SCRIPT_TIME_SHORT="$(date +%Y%m%dT%H%M%S%z)" # Save current date & time in ISO-8601 format (YYYYmmddTHHMMSS+zzzz).
	16	SCRIPT_DATE_SHORT="$(date +%Y%m%d)" # Save current date in ISO-8601 format.
	17
15d7fe72 SBS	18	#==BEGIN Define script parameters
	19	declare -Ag appRollCall # Associative array for storing app status (function checkapp())
	20	declare -Ag fileRollCall # Associative array for storing file status (function checkfile())
	21	#==END Define script parameters
	22
0d22dfcd	23	#== Function Definitions ==
1092c137	24
15d7fe72 SBS	25
15d7fe72 SBS	26	yell() { echo "$0: $*" >&2; } # Yell, Die, Try Three-Fingered Claw technique; # Ref/Attrib: https://stackoverflow.com/a/25515370
1092c137 SBS	27	die() { yell "$*"; exit 111; }
	28	try() { "$@" \|\| die "cannot $*"; }
	29
0d22dfcd SBS	30	echoerr() {
	31	# Usage: echo [ arguments ]
	32	# Description: Prints provided arguments to stderr.
	33	# Input: unspecified
	34	# Output: stderr
	35	# Script function dependencies: none
	36	# External function dependencies: echo
	37	# Last modified: 2020-04-11T21:16Z
	38	# Last modified by: Steven Baltakatei Sandoval
	39	# License: GPLv3+
	40	# Ref./Attrib:
	41	# [1]: # Roth, James (2010-06-07). ["How to print text to stderr instead of stdout"](https://stackoverflow.com/a/2990533). Licensed CC BY-SA 4.0.
	42
	43	echo "$@" 1>&2; # Define stderr echo function. See [1].
	44	return 0; # Function finished.
	45	} # Define stderr message function.
	46	vbm() {
	47	# Usage: vbm "DEBUG:verbose message here"
	48	# Description: Prints verbose message ("vbm") to stderr if OPTION_VERBOSE is set to "true".
	49	# Input:
	50	# - OPTION_VERBOSE variable set by processArguments function. (ex: "true", "false")
	51	# - "$@" positional arguments fed to this function.
	52	# Output: stderr
	53	# Script function dependencies: echoerr
	54	# External function dependencies: echo
	55	# Last modified: 2020-04-11T23:57Z
	56	# Last modified by: Steven Baltakatei Sandoval
	57	# License: GPLv3+
	58	# Ref./Attrib:
	59
	60	if [ "$OPTION_VERBOSE" == "true" ]; then
	61	FUNCTION_TIME=$(date --iso-8601=ns); # Save current time in nano seconds.
	62	echoerr "[$FUNCTION_TIME] ""$@"; # Display argument text.
	63	fi
	64
	65	# End function
	66	return 0; # Function finished.
	67	} # Verbose message display function.
1092c137 SBS	68	run() {
	69	# Usage: run [cmd]
	70	# Description: Runs command; reports success if command exit code 0; exits otherwise.
	71	# Input: none
	72	# Output: stdout
	73	# Script function dependencies: none
	74	# Last modified: 2020-06-19T22:09Z
	75	# Last modified by: Steven Baltakatei Sandoval
	76	# License: GPLv3+
	77	# Ref.Attrib: https://stackoverflow.com/a/18880585
	78	cmd_output=$(eval $1)
	79	return_value=$?
	80	if [ $return_value != 0 ]; then
	81	echo "Command $1 failed";
	82	exit -1;
	83	else
	84	echo "output: $cmd_output";
	85	echo "Command succeeded.";
	86	fi
	87	return $return_value
	88	} #
0d22dfcd SBS	89	showUsage() {
	90	# Usage: showUsage
	91	# Description: Displays script usage information.
	92	# Input: none
	93	# Output: stderr
	94	# Script function dependencies: echoerr
	95	# External dependencies: bash (5.0.3), echo
fdf917e1	96	# Last modified: 2020-05-04T16:11Z
0d22dfcd SBS	97	# Last modified by: Steven Baltakatei Sandoval
	98	# License: GPLv3+
	99	# Ref./Attrib.:
fdf917e1	100
0d22dfcd	101	echoerr "USAGE:"
fdf917e1	102	echoerr " bktemplate.sh [ options ]"
0d22dfcd SBS	103	echoerr
0d22dfcd SBS	104	echoerr "OPTIONS:"
0d22dfcd SBS	105	echoerr " -h, --help"
	106	echoerr " Display help information."
	107	echoerr
	108	echoerr " --version"
	109	echoerr " Display script version."
	110	echoerr
	111	echoerr " -v, --verbose"
	112	echoerr " Display debugging info."
	113	echoerr
	114	echoerr " -o, --output-file [ file ]"
	115	echoerr " Specify output file."
	116	echoerr
	117	echoerr " -i, --input-file [ file ]"
	118	echoerr " Specify input file."
	119	echoerr
	120	echoerr " -o, --output-dir [ directory ]"
	121	echoerr " Specify output directory."
	122	echoerr
	123	echoerr " -i, --input-dir [ directory ]"
	124	echoerr " Specify input directory."
	125	echoerr
	126
0d22dfcd SBS	127	# End function
	128	return 0; # Function finished.
	129	} # Display information on how to use this script.
	130	showVersion() {
	131	# Usage: showVersion
	132	# Descriptoin: Displays script version and license information.
	133	# Input: unspecified
	134	# Output: stderr
	135	# Script function dependencies: echoerr
	136	# External function dependencies: echo
	137	# Last modified: 2020-04-11T23:57Z
	138	# Last modified by: Steven Baltakatei Sandoval
	139	# License: GPLv3+
	140	# Ref./Attrib:
	141
	142	# Initialize function
	143	vbm "DEBUG:showVersion function called."
	144
	145	# Perform work
	146	OUTPUT="$SCRIPT_VERSION"
	147
	148	# Display results
	149	echoerr "$OUTPUT";
	150
	151	# End function
	152	vbm "DEBUG:showVersion function ended."
	153	return 0; # Function finished.
	154	} # Display script version.
	155	processArguments() {
	156	# Usage: processArguments "$@"
	157	# Description: Processes provided arguments in order to set script option variables useful for
	158	# changing how other functions behave. For example, it may:
	159	# 1. Activate verbose mode
	160	# Input: "$@" (list of arguments provided to the function)
	161	# Output: Sets following variables used by other functions:
	162	# OPTION_VERBOSE Indicates verbose mode enable status. (ex: "true", "false")
	163	# DIROUT1 Path to output directory.
	164	# FILEOUT1 Path to output file.
	165	# DIRIN1 Path to input directory.
	166	# FILEIN1 Path to input file.
	167	# OPTION_FILEOUT1_OVERWRITE Indicates whether file FILEOUT1 should be overwritten (ex: "true", "false')
0d22dfcd SBS	168	# Script function dependencies:
	169	# - echoerr Displays messages to stderr.
	170	# - vbm Displays messsages to stderr if OPTION_VERBOSE set to "true".
	171	# External dependencies: bash (5.0.3), echo
fdf917e1	172	# Last modified: 2020-05-04T14:41Z
0d22dfcd SBS	173	# Last modified by: Steven Baltakatei Sandoval
	174	# License: GPLv3+
	175	# Ref./Attrib.:
	176	# [1]: Marco Aurelio (2014-05-08). "echo that outputs to stderr". https://stackoverflow.com/a/23550347
	177
	178	# Initialize function
	179	#vbm "DEBUG:processArguments function called."
	180
	181	# Perform work
	182	while [ ! $# -eq 0 ]; do # While number of arguments ($#) is not (!) equal to (-eq) zero (0).
	183	#1>&2 echo "DEBUG:Starting processArguments while loop." # Debug stderr message. See [1].
	184	#1>&2 echo "DEBUG:Provided arguments are:""$@" # Debug stderr message. See [1].
	185	case "$1" in
	186	-h \| --help) showUsage; exit 1;; # Display usage.
	187	--version) showVersion; exit 1;; # Show version
	188	-v \| --verbose) OPTION_VERBOSE="true"; vbm "DEBUG:Verbose mode enabled.";; # Enable verbose mode. See [1].
	189	-i \| --input-file) # Define input file path
	190	if [ -f "$2" ]; then # If $2 is file that exists, set FILEIN1 to $2, pop $2.
	191	FILEIN1="$2";
	192	shift;
	193	vbm "DEBUG:Input file FILEIN1 set to:""$2";
	194	else
	195	echoerr "ERROR: Specified input file does not exist:""$2";
	196	echoerr "Exiting.";
	197	exit 1;
	198	fi ;;
fdf917e1	199	-I \| --input-dir) # Define input directory path
0d22dfcd SBS	200	if [ -d "$2" ]; then # If $2 is dir that exists, set DIRIN1 to $2, pop $2.
	201	DIRIN1="$2";
	202	shift;
	203	vbm "DEBUG:Input directory DIRIN1 set to:""$2";
	204	else # Display error if $2 is not a valid dir.
	205	echoerr "ERROR:Specified input directory does not exist:""$2";
	206	echoerr "Exiting.";
	207	exit 1;
	208	fi ;;
	209	-o \| --output-file) # Define output file path
	210	if [ -f "$2" ]; then # If $2 is file that exists, prompt user to continue to overwrite, set FILEOUT1 to $2, pop $2.
	211	echoerr "Specified output file $2 already exists. Overwrite? (y/n):"
	212	read m; case $m in
	213	y \| Y \| yes) OPTION_FILEOUT1_OVERWRITE="true";;
	214	n \| N \| no) OPTION_FILEOUT1_OVERWRITE="false";;
	215	*) echoerr "Invalid selection. Exiting."; exit 1;;
	216	esac
	217	if [ "$OPTION_FILEOUT1_OVERWRITE" == "true" ]; then
	218	FILEOUT1="$2";
	219	shift;
	220	vbm "DEBUG:Output file FILEOUT1 set to:""$2";
	221	else
	222	echoerr "ERORR:Exiting in order to not overwrite output file:""$FILEOUT1";
	223	exit 1;
	224	fi
	225	else
	226	FILEOUT1="$2";
	227	shift;
	228	vbm "DEBUG:Output file FILEOUT1 set to:""$2";
	229	fi ;;
	230	-O \| --output-dir) # Define output directory path
	231	if [ -d "$2" ]; then # If $2 is dir that exists, set DIROUT1 to $2, pop $2
	232	DIROUT1="$2";
	233	shift;
	234	vbm "DEBUG:Output directory DIROUT1 set to:""$2";
	235	else
	236	echoerr "ERROR:Specified output directory is not valid:""$2";
	237	echoerr "Exiting.";
	238	exit 1;
fdf917e1 SBS	239	fi ;;
fdf917e1 SBS	240	*) echoerr "ERROR: Unrecognized argument."; exit 1;; # Handle unrecognized options. See [1].
0d22dfcd	241	esac
fdf917e1	242	shift
0d22dfcd SBS	243	done
	244
	245	# End function
	246	vbm "DEBUG:processArguments function ended."
	247	return 0; # Function finished.
	248	} # Evaluate script options from positional arguments (ex: $1, $2, $3, etc.).
	249	checkExecutables() {
	250	# Usage: checkExecutables [ command1 ] [ command2 ] [...] [ commandN ]
fdf917e1	251	# Description: Checks that provided commands exist and displays those that do not exist.
0d22dfcd SBS	252	# Input:
	253	# - command names (arguments)
	254	# Output: commands that don't exist (stderr)
	255	# Script function dependencies:
	256	# - echoerr for displaying errors via stderr
	257	# - processArguments for setting OPTION_VERBOSE
	258	# - vbm for displaying verbose messages if OPTION_VERBOSE is "true"
	259	# External dependencies: bash (5.0.3), command
fdf917e1	260	# Last modified: 2020-04-11T23:59Z
0d22dfcd SBS	261	# Last modified by: Steven Baltakatei Sandoval
	262	# License: GPLv3+
	263	# Ref./Attrib.:
	264	# [1]: SiegeX (2010-12-12). ["Difference between return and exit in Bash functions."](https://stackoverflow.com/a/4419971). Licensed CC BY-SA 4.0.
	265	# [2]: Darryl Hein (2009-12-23). ["Add a new element to an array without specifying the index in Bash"](https://stackoverflow.com/a/1951523). Licensed CC BY-SA 4.0.
	266	# [3]: kojiro (2012-10-03). ["Convert command line arguments into an array in Bash"](https://stackoverflow.com/a/12711853)
	267	# [4]: niieani (2016-01-12). ["How to copy an array in Bash?"](https://stackoverflow.com/a/34733375/10850071). Licensed CC BY-SA 4.0.
	268
	269	# Initialize function
	270	vbm "DEBUG:checkExecutables function called."
	271	declare -a candidateCommandsNames # Initialize array for storing positional arguments provided to this function.
	272	candidateCommandsNames=("$@") # Save positional arguments to variable as string. See [3].
	273	vbm "DEBUG:candidateCommandsNames:""$@"
	274	vbm "DEBUG:candidateCommandsNames[0]:""${candidateCommandsNames[0]}"
	275	vbm "DEBUG:candidateCommandsNames[1]:""${candidateCommandsNames[1]}"
	276	vbm "DEBUG:candidateCommandsNames[2]:""${candidateCommandsNames[2]}"
	277	declare -a outputInvalidCommandsArray # Initialize arary for storing names of invalid commands.
	278	declare -a outputValidCommandsArray # Initialize array for storing names of valid commands.
	279
	280	# Perform work
	281	for candidateCommandName in "${candidateCommandsNames[@]}"; do # Search through all space-delimited text for valid commands.
	282	if command -v "$candidateCommandName" 1>/dev/null 2>/dev/null; then # Check if a command is valid or not.
	283	outputValidCommandsArray+=("$candidateCommandName") ; # See [2].
	284	vbm "DEBUG:Adding $candidateCommandName to outputValidCommandsArray."
	285	else
	286	outputInvalidCommandsArray+=("$candidateCommandName") ; # See [2].
	287	vbm "DEBUG:Adding $candidateCommandName to outputInvalidCommandsArray."
	288	fi
	289	done
	290
	291	# Output results
	292	if [ ${#outputInvalidCommandsArray[@]} -gt 0 ]; then # if number of elements in outputInvalidCommandsArray greater than 0, then display offending commands and exit 1.
	293	echoerr "ERROR: Invalid commands found:""${outputInvalidCommandsArray[@]}"; # display invalid commands as error
	294	exit 1; # See [1].
	295	elif [ ${#outputInvalidCommandsArray[@]} -eq 0 ]; then # if number of elements in outputInvalidCommandsArray equals zero, then return 0.
	296	vbm "DEBUG: Valid commands are:""${outputValidCommandsArray[@]}"; # display valid commands if verbose mode enabled
	297	return 0; # See [1].
	298	else
	299	echoerr "ERROR: Check outputInvalidCommandsArray.";
	300	fi
	301
	302	# End function
	303	vbm "DEBUG:checkExecutables function ended."
	304	return 0; # Function finished.
	305	} # Check that certain executables exist.
	306	updateTimeConstants() {
	307	# Usage: updateTimeConstants
	308	# Description: Updates time-related variables for use by other scripts.
	309	# Input: (none)
	310	# Output: Sets following variables:
	311	# TIME_CURRENT Current time in long ISO-8601 format. (ex: YYYY-mm-ddTHH:MM:SS+ZZZZ)
	312	# TIME_CURRENT_SHORT Current time in short ISO-8601 format. (ex: YYYYmmddTHHMMSS+ZZZZ)
	313	# DATE_CURRENT Current date in ISO-8601 format. (ex: YYYY-mm-dd)
	314	# DATE_CURRENT_SHORT Current date in short ISO-8601 format. (ex: YYYYmmdd)
	315	# DATE_TOMORROW Tomorrow's date in ISO-8601 format. (ex: YYYY-mm-dd)
	316	# TIME_NEXT_MIDNIGHT Time of tomorrow's midnight in long (ex: YYYY-mm-ddTHH:MM:SS+ZZZZ)
	317	# ISO-861 format.
	318	# SEC_TIL_MIDNIGHT Seconds until next midnight.
	319	# Script function dependencies:
	320	# - echoerr for displaying errors via stderr
	321	# - processArguments for setting OPTION_VERBOSE
	322	# - vbm for displaying verbose messages if OPTION_VERBOSE is "true"
	323	# External dependencies: bash (5.0.3), date, echo
	324	# Last modified: 2020-04-11T23:59Z
325	# Last modified by: Steven Baltakatei Sandoval
326	# License: GPLv3+
327	# Ref./Attrib.:
328
329	# Initialize function
330	vbm "DEBUG:updateTimeConstants function called."
331
332	# Perform work
333	TIME_CURRENT="$(date --iso-8601=seconds)" ;
334	TIME_CURRENT_SHORT="$(date -d "$TIME_CURRENT" +%Y%m%dT%H%M%S%z)"
335	DATE_CURRENT="$(date -d "$TIME_CURRENT" --iso-8601=date)" ;
336	DATE_CURRENT_SHORT="$(date -d "$TIME_CURRENT" +%Y%m%d)" ;
337	DATE_TOMORROW="$(date -d "$TIME_CURRENT next day" --iso-8601=date)" ;
338	TIME_NEXT_MIDNIGHT="$(date -d "$DATE_TOMORROW" --iso-8601=seconds)" ;
339	SECONDS_UNTIL_NEXT_MIDNIGHT="$(( $(date +%s -d "$TIME_NEXT_MIDNIGHT") - $(date +%s -d "$TIME_CURRENT") ))" ;
340
341	# End function
342	vbm "DEBUG:updateTimeConstants function ended."
343	return 0; # Function finished.
344	} # Update time constants
15d7fe72 SBS	345	checkapp() {
	346	# Desc: If arg is a command, save result in assoc array 'appRollCall'
	347	# Usage: checkapp arg1 arg2 arg3 ...
	348	# Input: global assoc. array 'appRollCall'
	349	# Output: adds/updates key(value) to global assoc array 'appRollCall'
	350	local returnState
	351	#echo "DEBUG:$(date +%S.%N)..Starting checkapp function."
	352	#echo "DEBUG:args: $@"
	353	#echo "DEBUG:returnState:$returnState"
	354
	355	#===Process Args===
	356	for arg in "$@"; do
	357	#echo "DEBUG:processing arg:$arg"
	358	if command -v $arg 1>/dev/null 2>&1; then # Check if arg is a valid command
	359	appRollCall[$arg]="true";
	360	#echo "DEBUG:appRollCall[$arg]:"${appRollCall[$arg]}
	361	if ! [ "$returnState" = "false" ]; then returnState="true"; fi
	362	else
	363	appRollCall[$arg]="false"; returnState="false";
	364	fi
	365	done
	366
	367	#for key in "${!appRollCall[@]}"; do echo "DEBUG:$key => ${appRollCall[$key]}"; done
	368	#echo "DEBUG:evaluating returnstate. returnState:"$returnState
	369
	370	#===Determine function return code===
	371	if [ "$returnState" = "true" ]; then
	372	#echo "DEBUG:checkapp returns true for $arg";
	373	return 0;
	374	else
	375	#echo "DEBUG:checkapp returns false for $arg";
	376	return 1;
	377	fi
	378	} # Check that app exists
	379	checkfile() {
	380	# Desc: If arg is a file path, save result in assoc array 'fileRollCall'
	381	# Usage: checkfile arg1 arg2 arg3 ...
	382	# Input: global assoc. array 'fileRollCall'
	383	# Output: adds/updates key(value) to global assoc array 'fileRollCall';
	384	# Output: returns 0 if app found, 1 otherwise
	385	local returnState
	386
	387	#===Process Args===
	388	for arg in "$@"; do
	389	#echo "DEBUG:processing arg:$arg"
	390	if [ -f "$arg" ]; then
	391	fileRollCall["$arg"]="true";
	392	#echo "DEBUG:fileRollCall[\"$arg\"]:"${fileRollCall["$arg"]}
	393	if ! [ "$returnState" = "false" ]; then returnState="true"; fi
	394	else
	395	fileRollCall["$arg"]="false"; returnState="false";
	396	fi
	397	done
	398
	399	#for key in "${!fileRollCall[@]}"; do echo "DEBUG:fileRollCall key [$key] is:${fileRollCall[$key]}"; done
	400	#echo "DEBUG:evaluating returnstate. returnState:"$returnState
	401
	402	#===Determine function return code===
	403	if [ "$returnState" = "true" ]; then
	404	#echo "DEBUG:checkapp returns true for $arg";
	405	return 0;
	406	else
	407	#echo "DEBUG:checkapp returns false for $arg";
	408	return 1;
409	fi
410	} # Check that file exists
411
0d22dfcd SBS	412
	413	#== Main Program Definition ==
	414	main() {
	415	# Usage: main "$@" # See [1].
	416	# Input: unspecified (note: all Global Constants declared at beginning of script assumed to be available)
	417	# OPTION_VERBOSE (used by vbm, set by processArguments) (ex: "true", "false")
0d22dfcd SBS	418	# Output: unspecified
	419	# Script function dependencies:
	420	# - echoerr for displaying errors via stderr
	421	# - vbm for displaying verbose messages if OPTION_VERBOSE is "true"
	422	# - processArguments for setting OPTION_VERBOSE
	423	# - checkExecutables for checking that specified commands are available
	424	# External dependencies: bash (5.0.3), echo
fdf917e1	425	# Last modified: 2020-05-04T16:50Z
0d22dfcd SBS	426	# Last modified by: Steven Baltakatei Sandoval
	427	# License: GPLv3+
	428	# Ref./Attrib.:
	429	# [1]: ErichBSchulz (2011-11-20). [How to correctly pass bash script arguments to functions](https://stackoverflow.com/a/8198970). Licensed CC BY-SA 4.0.
	430
	431	# Initialize function
	432	processArguments "$@" # Process arguments.
	433	vbm "DEBUG:main function called."
	434	vbm "DEBUG:main function arguments are:""$@"
fdf917e1	435	checkExecutables "echo" "date" "cut" "awk" # Confirm that executables necessary to run are available. Exit if any fail.
0d22dfcd SBS	436
0d22dfcd SBS	437	# Process inputs
fdf917e1 SBS	438	if [ -v FILEIN1 ]; then # VERBOSE: Display contents of FILEIN1 if FILEIN1 has been set.
	439	vbm "DEBUG:main function detects input file:""$FILEIN1" ;
	440	vbm "DEBUG:contents of following file is displayed below:""$FILEIN1" ;
	441	if [ "$OPTION_VERBOSE" == "true" ]; then # display FILEIN1 contents via cat if verbose mode specified
	442	echoerr "========""$FILEIN1"" START""========" ;
	443	cat "$FILEIN1" 1>&2 ;
	444	echoerr "========""$FILEIN1"" END""========" ;
	445	fi
0d22dfcd	446	fi
0d22dfcd SBS	447
0d22dfcd SBS	448	# Perform work
fdf917e1 SBS	449	OUTPUT="$OUTPUT""Hello world.\n"
	450	if [ -v FILEIN1 ]; then
	451	OUTPUT="$OUTPUT""The b2sum hash of $FILEIN1 is: $(b2sum "$FILEIN1" \| awk '{print $1}').\n";
	452	fi
	453	OUTPUT="$OUTPUT""The current time is:""$SCRIPT_TIME_SHORT\n"
0d22dfcd SBS	454
	455	# Output results
	456	echo -e "$OUTPUT"
	457
	458	if [ -v FILEOUT1 ]; then # if FILEOUT1 set, write to this file.
fdf917e1	459	vbm "DEBUG:main function detects output file:""$FILEOUT1" ;
0d22dfcd SBS	460	echo -e "$OUTPUT" > "$FILEOUT1" ;
	461	vbm "DEBUG:main funtion wrote OUTPUT to:""$FILEOUT1" ;
	462	elif [ -v DIROUT1 ]; then # else if DIROUT1 set, set FILEOUT1 to timestamped filename, combine into PATHOUT1, write output to PATHOUT1.
fdf917e1 SBS	463	vbm "DEBUG:main function detects output directory:""$DIROUT1" ;
fdf917e1 SBS	464	FILEOUT1="$SCRIPT_TIME_SHORT"..output
0d22dfcd SBS	465	PATHOUT1="$DIROUT1"/"$FILEOUT1"
	466	echo -e "$OUTPUT" > $PATHOUT1 ;
	467	vbm "DEBUG:main function wrote output file to:""$PATHOUT1" ;
	468	fi
	469
	470	# End function
	471	vbm "DEBUG:main function ended."
	472	return 0; # Function finished.
	473	}
	474
	475	#== Perform work and exit ==
	476	main "$@" # Run main function.
	477	exit 0;