import shellscript

onfilechange.sh

+#!/bin/bash
+# ======================================================================
+#
+#
+#  T R I G G E R    C O M M A N D    O N    A    F I L E C H A N G E
+#
+#
+# A Shell script that watches a given file or multiple files. 
+# If the file changes then a given command will be exxecuted.
+# It loops permanently; you need to stop it by Ctrl + C and/ or can
+# use it as systemd watcher daemon.
+#
+# It uses stats for wide compatibility but prefers inotifywatch to
+# check a file change.
+#
+# licence: GNU GPL 3.0
+#
+# ----------------------------------------------------------------------
+# 2019-10-14  v1.0  <axel.hahn@iml.unibe.ch>  first basic version
+# ======================================================================
+
+# ----------------------------------------------------------------------
+# CONFIG
+# ----------------------------------------------------------------------
+
+bDebug=0
+iSleep=5
+sCommand=
+sWatchFile=
+sMode=
+
+# ---- below are some internal variables 
+sVersion=1.0
+
+
+# ----------------------------------------------------------------------
+# FUNCTIONS
+# ----------------------------------------------------------------------
+
+# show help
+function showHelp(){
+cat <<ENDOFHELP
+HELP:
+        This script checks the change of a given file and triggers
+        a command if it changes
+
+PRAMETERS:
+        -c [command]
+            command to execute on a file change
+        -f [filename(s)]
+            filenames to watch; separate multiple files with space and put all in quotes
+        -h
+            show this help
+        -i
+            force inotifywait command
+        -s
+	        force stats command
+        -v
+            verbose mode; enable showing debug output
+        -w [integer]
+            for stats mode: wait time in seconds betweeen each test or on missing file; default: 5 sec
+
+EXAMPLES:
+        `basename $0` -f /home/me/touchfile.txt -c "ls -l" 
+            watch touchfile.txt and make a file listing on change
+
+        `basename $0` -f "/home/me/touchfile.txt home/me/touchfile2.txt" -c "ls -l" 
+            watch touchfile.txt and touchfile2.txt
+
+        `basename $0` -f /home/me/touchfile.txt -s -w 10 -c "ls -l" 
+            watch touchfile.txt every 10 sec with stats and make a file listing on change
+
+ENDOFHELP
+
+}
+
+# write debug output ... if debug is enabled only
+#
+# global (bool) $bDebug
+# param  string  text message to show
+function wd(){
+	if [ $bDebug -ne 0 ]; then
+		echo "[`date`] DEBUG " $*
+	fi
+}
+
+# list watched files
+#
+# global (string) filename(s) to watch
+function listFiles(){
+	echo
+	echo ">>>>> watched files"
+	ls -ld ${sWatchFile} 2>&1
+}
+
+# for stats: helper to get current file status
+#
+# global (string) $sWatchFile
+function getFilestatus(){
+	for myfile in ${sWatchFile}
+	do
+		stat -c "%F %n | perms: %A; user %u (%U) group %g (%G) | size: %s byte | last modification %y" "${myfile}" 2>&1
+	done
+}
+
+# for stats: inititalize file change detection
+#
+# global (string) $TmpFile    last/ initial file status
+# global (string) $sTmpFile2  current file status
+function initFilestatus(){
+	getFilestatus >${sTmpFile}
+	wd "`cat ${sTmpFile}`"
+	cp -p ${sTmpFile} ${sTmpFile2}
+}
+
+# for stats: compare file status and execute command on change
+#
+# global (string) $TmpFile    last/ initial file status
+# global (string) $sTmpFile2  current file status
+# global (string) $sCommand   command to execute
+function compareFilestatus(){
+	getFilestatus >${sTmpFile2}
+	wd "`cat ${sTmpFile2}`"
+	diff ${sTmpFile} ${sTmpFile2}
+	if [ $? -eq 0 ]; then
+		wd "No Change"
+	else
+		wd "Change detected."
+		execCommand
+		if [ $? -eq 0 ]; then
+			echo Command was successfuil. 
+			echo
+			wd "Re-Init File status"
+			initFilestatus
+		else
+			echo FAILED.
+		fi
+	fi
+}
+
+# execute a command; called on a file change
+#
+# global (string) $sCommand  command line to exectute
+function execCommand(){
+	listFiles
+	echo 
+	echo ">>>>> `date` Executing ${sCommand} ..."
+	${sCommand}
+}
+
+# ----------------------------------------------------------------------
+# MAIN
+# ----------------------------------------------------------------------
+
+cat <<ENDOFHEAD
+____________________________________________________________________________________
+
+  T R I G G E R    C O M M A N D    O N    A    F I L E C H A N G E
+____________________________________________________________________________________
+                                                                                v${sVersion}
+
+ENDOFHEAD
+
+which inotifywait >/dev/null 2>&1
+if [ $? -ne 0 ]; then
+	echo ERROR: the command inotify was not found on your system,
+	which stat >/dev/null 2>&1
+	if [ $? -ne 0 ]; then
+		echo ERROR: the command stat was not found on your system,
+		exit 2
+	fi
+	echo "INFO: enabling compatibility mode with stats command"
+	sMode=stats
+else
+	echo "INFO: inotifywait command detected"
+	sMode=inotifywait
+fi
+
+if [ $# -eq 0 ]; then
+	showHelp
+	exit 0
+fi
+
+while getopts ":c: :v :f: :h :i :s :w:" opt
+do
+        case $opt in
+                \?|h)
+                        showHelp
+                        exit 0
+                        ;;
+		v)
+			bDebug=1
+			wd "debug is now ${bDebug}"
+			;;
+		c)
+			sCommand=$OPTARG
+			wd "command is now ${sCommand}"
+			;;
+		f)
+			sWatchFile=$OPTARG
+			wd "watch file is now ${sWatchFile}"
+			;;
+		i)
+			sMode=inotifywait
+			wd "forcing mode with inotifywait command"
+			;;
+		s)
+			sMode=stats
+			wd "forcing mode with stats command"
+			;;
+                w)
+                        typeset -i iSleep=$OPTARG
+                        wd "sleep $iSleep sec"
+                        ;;
+                :)
+                        echo "ERROR: Option -$opt requires an argument." >&2
+                        showHelp
+                        exit 1
+        esac
+done
+
+cat <<ENDOFINFO
+checking file [${sWatchFile}]
+with command [${sMode}] 
+with a sleep time of  [${iSleep}] seconds 
+and on change start command [${sCommand}]
+
+...............................................................................
+
+
+ENDOFINFO
+
+# ----------------------------------------------------------------------
+# CHECKS
+# ----------------------------------------------------------------------
+
+wd "--- checks"
+if [ -z "${sWatchFile}" ]; then
+	echo ERROR: set a check file with param -f
+	exit 1
+fi
+listFiles
+if [ $? -ne 0 ]; then
+	echo "INFO: file ${sWatchFile} (or one of them) does not exist yet"
+	# echo "ERROR: file ${sWatchFile} (or one of them) does not exist yet"
+	# exit 1
+fi
+
+if [ -z "${sCommand}" ]; then
+	echo ERROR: set a ${sCommand} with param -s
+	exit 1
+fi
+
+# ----------------------------------------------------------------------
+# GO
+# ----------------------------------------------------------------------
+
+myset=`echo ${sWatchFile} | sha1sum | cut -f 1 -d " "`
+sTmpFile="/tmp/`basename $0`-${myset}-last.tmp"
+sTmpFile2="/tmp/`basename $0`-${myset}-current.tmp"
+
+case $sMode in
+	"inotifywait")
+		while true; do
+			listFiles >/dev/null 2>&1 
+			if [ $? -eq 0 ]; then
+				inotifywait -e attrib -e modify ${sWatchFile} && execCommand
+			else 
+				wd sleep ${iSleep}
+				sleep ${iSleep}
+				echo "WARNING: inotifywait only can notify if all watched files exist. You can use -s to use stats for file detection"
+			fi
+		done
+		;;
+
+	"stats")
+		wd "--- init"
+		initFilestatus
+		echo waiting for file changes ...
+
+		wd "--- starting loop"
+		while true; do
+			wd sleep ${iSleep}
+			sleep ${iSleep}
+			compareFilestatus
+		done
+		;;
+esac
+
+# ----------------------------------------------------------------------