#!/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 ).
#==BEGIN Variable Initialization==
#===BEGIN 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.
#===END Global constants===
#===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
#==END Variable Initialization==
#==BEGIN 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 $arg";
return 1;
fi
} # Check that file exists
main() {
# Usage: main "$@" # 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.
} # Main function
#==END Function Definitions==
#==BEGIN Perform work and exit==
main "$@" # Run main function.
exit 0;
#==END Perform work and exit==