#!/bin/bash
# ¹®ÀÚ¿­À» ÇÊÅ͸µÇϱâ À§Çؼ­ "case" ±¸¹® ¾²±â.

SUCCESS=0
FAILURE=-1

isalpha ()  # ÀÔ·Â ¹®ÀÚ¿­ÀÇ "ù¹ø° ¹®ÀÚ"°¡ ¾ËÆĺªÀÎÁö ¾Æ´ÑÁö È®ÀÎ.
{
if [ -z "$1" ]                # ÀÎÀÚ ¾øÀÌ ³Ñ¾î¿Ô±º.
then
  return $FAILURE
fi

case "$1" in
[a-zA-Z]*) return $SUCCESS;;  # ¹®ÀÚ·Î ½ÃÀÛÇÏ´ÂÁö.
*        ) return $FAILURE;;
esac
}             # C ÀÇ "isalpha()" ÇÔ¼ö¿Í ºñ±³ÇØ º¸¼¼¿ä.


isalpha2 ()   # "¹®ÀÚ¿­ Àüü"°¡ ¾ËÆĺªÀÎÁö È®ÀÎ.
{
  [ $# -eq 1 ] || return $FAILURE

  case $1 in
  *[!a-zA-Z]*|"") return $FAILURE;;
               *) return $SUCCESS;;
  esac
}



check_var ()  # isalpha() ÀÇ ÇÁ·ÐÆ®¿£µå(front-end)
{
if isalpha "$@"
then
  echo "$* = ¾ËÆĺª"
else
  echo "$* = ¾ËÆĺª ¾Æ´Ô"  # ÀÎÀÚ°¡ ¾ø¾îµµ "¾ËÆĺª ¾Æ´Ô"ÀÓ.
fi
}

a=23skidoo
b=H3llo
c=-What?
d=`echo $b`   # ¸í·É¾î ġȯ.

check_var $a
check_var $b
check_var $c
check_var $d
check_var     # ÀÎÀÚ¾øÀÌ ºÎ¸£¸é ¾î¶»°Ô µÉ±î¿ä?


# S.C. °¡ ´õ ÁÁ°Ô °íħ.

exit 0