script-template.sh

#!/bin/bash
#================================================================
#% SYNOPSIS
#+    ${SCRIPT_NAME} [-hv] [-o[file]] args ...
#%
#% DESCRIPTION
#%    This is a script template
#%    to start any good shell script.
#%
#% OPTIONS
#%    -o [file], --output=[file]    Set log file (default=/dev/null)
#%                                  use DEFAULT keyword to autoname file
#%                                  The default value is /dev/null.
#%    -t, --timelog                 Add timestamp to log ("+%y/%m/%d@%H:%M:%S")
#%    -x, --ignorelock              Ignore if lock file exists
#%    -h, --help                    Print this help
#%    -v, --version                 Print script information
#%
#% EXAMPLES
#%    ${SCRIPT_NAME} -o DEFAULT arg1 arg2
#%
#================================================================
#- IMPLEMENTATION
#-    version         ${SCRIPT_NAME} (www.uxora.com) 0.0.4
#-    author          Michel VONGVILAY
#-    copyright       Copyright (c) http://www.uxora.com
#-    license         GNU General Public License
#-    script_id       12345
#-
#================================================================
#  HISTORY
#     2015/03/01 : mvongvilay : Script creation
#     2015/04/01 : mvongvilay : Add long options and improvements
# 
#================================================================
#  DEBUG OPTION
#    set -n  # Uncomment to check your syntax, without execution.
#    set -x  # Uncomment to debug this shell script
#
#================================================================
# END_OF_HEADER
#================================================================

SUBJECT=$(od -x /dev/urandom | head -1 | awk '{OFS="-"; print $2$3,$4,$5,$6,$7$8$9}')
VERSION=0.1.0
USAGE="Usage: command -hv args"

# Script operational configuration directives.
LOGGING="screenonly"		# Values can be 'screenonly', 'fileonly', 'both'
LOGFILE="/var/log/${SCRIPT_NAME}.log"
TRAPERRORS=${TRUE}
MINOPTCOUNT=0

# --- Error Trapping --------------------------------------------
set -e
set -o pipefail  # trace ERR through pipes
set -o errtrace  # trace ERR through 'time command' and other functions
function trap-errors() {
	local lineno="${1}"
	local errmsg="${2}"
	local errcde="${3:-1}"

	if [[ -n "$errmsg" ]] ; then
		echo "Error on or near line ${lineno}: ${errmsg}; exiting with status ${code}"
	else
		echo "Error on or near line ${lineno}; exiting with status ${errcde}"
	fi
	exit "${errcde}"	
}
[[ ${TRAPERRORS} ]] && trap 'trap-errors ${lineno} ${?}' ERR

# --- Logging --------------------------------------------
case "${LOGGING}" in
  'screenonly')
		echo "All logging going to screen."
	;;
	
	'fileonly')
		echo "All logging now going to ${LOGFILE}"
		exec > "${LOGFILE}"
		exec 2>&1
	;;
	
	'both')
		echo "All logging now going to ${LOGFILE}"
		exec > "${LOGFILE}"
		exec 2>&1 | tee -a "${LOGFILE}"
	;;
esac

# --- Option processing --------------------------------------------


if [ $# -lt "${MINOPTCOUNT}" ] ; then
    echo $USAGE
    exit 1;
fi

while getopts ":Vh" optname
do
	case "$optname" in
	  "V")
		echo "Version $VERSION"
		exit 0;
		;;
	  "h")
		echo $USAGE
		exit 0;
		;;
	  "?")
		echo "Unknown option $OPTARG"
		exit 0;
		;;
	  ":")
		echo "No argument value for option $OPTARG"
		exit 0;
		;;
	  *)
		echo "Unknown error while processing options"
		exit 0;
		;;
	esac
done

shift $(($OPTIND - 1))

param1=$1
param2=$2
# -----------------------------------------------------------------

LOCK_FILE=/var/run/${SUBJECT}.lock

if [[ -f "$LOCK_FILE" ]]; then
	echo "Script is already running"
	exit
fi

# -----------------------------------------------------------------
trap "rm -f $LOCK_FILE" EXIT
touch $LOCK_FILE 

# -----------------------------------------------------------------
#  SCRIPT LOGIC GOES HERE
# -----------------------------------------------------------------

echo "Hello World."