Shell Programming and Scripting

<do stuff>
...
set -x
<execute desired command>
set +x
...
<do more stuff>

# Echoes the command first and then executes it.
# Any number of parameters may be supplied.
# Inside this function they will first be concatenated into a single string with a single space between each arg.
# This string must not be empty or all whitespace
echoThenExecute() {
	# concatenate all the individual args into a single string with a single space between the args:
	argsAsString=""
	while [ $# -ne 0 ]
	do
		argsAsString="$argsAsString ${1}"
		shift
	done

	if [ "$argsAsString" = "" ]; then
		echo "ERROR: empty command supplied"
		exit 1
	elif [ ! -n "`echo $argsAsString | sed 's/[[:space:]]*//g'`" ]; then	# note: the final g in the sed command makes it a global replacement, which is crucial; see http://www.grymoire.com/Unix/Sed.html
		echo "ERROR: all whitespace command supplied"
		exit 1
	fi

	echo "$argsAsString"
	bash -c "$argsAsString"
}

bash -xvc 'ls -l *'
 -or-
(set -x; ls -l *)

typeset CMD="cat | sed | grep | cut | awk -v foo.bar"
echo "$CMD"
eval $CMD

CMD="cat | sed | grep | cut | awk -v foo.bar"

$ cat typesettest
#! /usr/bin/ksh


function xyzzy
{
        typeset CMD=two
        echo in xyzzy CMD = $CMD
        return 0
}


CMD=one
echo CMD is $CMD
xyzzy
echo CMD still is $CMD
exit 0
$
$
$ ./typesettest
CMD is one
in xyzzy CMD = two
CMD still is one
$