Basis of Shell script.

basis-shell.sh

#!/bin/bash

cat <<_EOT_
# executing script name. Naming starting point is directory which call this scrip.
$0:              $0

# parent directory of executing script.
`dirname $0`:    `dirname $0`

# name of executing script.
${0##*/}:        ${0##*/}

# name of executing script.
`basename $0`:   `basename $0`

# the number of args you gave execution script.
\$#:              $#

# all values of args you gave executing script.
\$*:              $*

# flag if excuted just before command is succeed or not.
\$?:              $?
_EOT_