#!/bin/bash

username0=
# username0 ´Â ¼±¾ð¸¸ µÇ°í ³Î·Î ¼¼Æ®µÆ½À´Ï´Ù.
echo "username0 = ${username0-`whoami`}"
# ¿¡ÄÚ µÇÁö ¾Ê½À´Ï´Ù.

echo "username1 = ${username1-`whoami`}"
# username1 ´Â ¼±¾ðµÇÁö ¾Ê¾Ò½À´Ï´Ù.
# ¿¡ÄÚ µË´Ï´Ù.

username2=
# username2 ´Â ¼±¾ð¸¸ µÇ°í ³Î°í ¼¼Æ®µÆ½À´Ï´Ù.
echo "username2 = ${username2:-`whoami`}"
# Á¶°Ç Å×½ºÆ®½Ã - °¡ ¾Æ´Ï°í :- ¸¦ ½è±â ¶§¹®¿¡ ¿¡ÄÚ µË´Ï´Ù.

exit 0