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# scriptpath - determine own absolute path name
# Heiner Steven <heiner.steven@odn.de>, 2003-01-06
#
# Searches for the name of the script ($0) the way a shell would: first
# try to access the file directly, then search all directories in
# $PATH.
#
# Notes
#    o	The results are always unsure, because the program invoking the
#	script may have set $0 to an arbitrary (even wrong) value.
#    o	We check if a file is an regular file and if it is executable.
#    	Remove the [ -x ... ] checks if the former is sufficient.

myname=$0

# When "CDPATH" is set, "cd" sometimes prints the destination directory
# to standard output, which could corrupt x=`cd` output:

unset CDPATH

if [ -f "$myname" ] && [ -x "$myname" ]
then
    # $myname is already a valid file name. Chances are good
    # that it is our name.

    mypath=$myname
else

    case "$myname" in
	/*)			# absolute path - do not search PATH
	    echo >&2 "cannot find full path name: $myname"
	    exit 1
	    ;;

	*)
	    # Search all directories from the PATH variable. Take
	    # care to interpret leading and trailing ":" as meaning
	    # the current directory; the same is true for "::" within
	    # the PATH.

	    for dir in `echo "$PATH" |
	    	    sed 's/^:/.:/g;s/::/:.:/g;s/:$/:./;s/:/ /g'`
	    do
		#echo >&2 "DEBUG: dir=<$dir>"
		[ -f "$dir/$myname" ] || continue # no file
		[ -x "$dir/$myname" ] || continue # not executable
		mypath=$dir/$myname
		break		# only return first matching file
	    done
	    ;;
    esac
fi

if [ -f "$mypath" ]
then
    : # echo >&2 "DEBUG: mypath=<$mypath>"
else
    echo >&2 "cannot find full path name: $myname"
    exit 1
fi

# "Normalize" the path: resolve /./ and /../ directory specifications

dir=`echo "$mypath" | sed 's|^\(.*\)/[^/]*|\1|'` # dirname
file=`echo "$mypath" | awk -F/ '{print $NF}'`	# basename
#echo >&2 "DEBUG: dir=<$dir> file=<$file>"

if [ X"$dir" != X ] && [ -d "$dir" ]
then
    dir=`cd "$dir"; pwd`	# "pwd" always prints "normalized" paths
    abspath=$dir/
else
    abspath=
fi

abspath=$abspath$file
echo "$abspath"
exit 0