unitproc/bktemplate

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