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

#!/bin/bash

# Date: 2020-05-04T16:50Z
# 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.

#== Function Definitions ==
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.
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

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