#!/bin/bash

# º¯¼ö: ÇÒ´ç°ú ġȯ

a=375
hello=$a

#-------------------------------------------------------------------------
# º¯¼ö¸¦ ÃʱâÈ­ ÇÒ ¶§, = ¾çÂÊ¿¡´Â ºó Ä­ÀÌ µé¾î°¡¸é ¾È µË´Ï´Ù.

#  "VARIABLE =value" ¶ó°í Çϸé,
#+ ½ºÅ©¸³Æ®´Â "VARIABLE" ¸í·É¾î°¡ "=value"¶õ ÀÎÀÚ¸¦ °®´Â°Íó·³ ÀνÄÇÕ´Ï´Ù.

#  "VARIABLE= value" ¶ó°í Çϸé,
#+ ½ºÅ©¸³Æ®´Â "value" ¸í·É¾î°¡ ȯ°æº¯¼ö "VARIABLE"À» ""·Î ¼¼ÆÃÇؼ­ 
#+ ½ÇÇàµÇ´Â °ÍÀ¸·Î ÀνÄÇÕ´Ï´Ù.
#-------------------------------------------------------------------------


echo hello    # º¯¼ö ÂüÁ¶°¡ ¾Æ´Ï°í ±×³É "hello"¶õ ¹®ÀÚ¿­ÀÔ´Ï´Ù.

echo $hello
echo ${hello} # À§¿Í ¶È°°½À´Ï´Ù.

echo "$hello"
echo "${hello}"

echo

hello="A B  C   D"
echo $hello
echo "$hello"
# ÀÌÁ¦ echo $hello ¿Í echo "$hello" ´Â ´Ù¸¥ °á°ú°¡ ³ª¿É´Ï´Ù.
# º¯¼ö¸¦ Äõ¿ìÆÃÇØÁÖ¸é °ø¹é¹®ÀÚ°¡ º¸Á¸µË´Ï´Ù.

echo

echo '$hello'
#  ÀÛÀº µû¿ÈÇ¥·Î º¯¼ö¸¦ Äõ¿ìÆÃÇØÁÖ¸é "$"°¡ ¹®ÀÚ ±×´ë·Î Çؼ®µÇ±â ¶§¹®¿¡
#+ º¯¼ö ÂüÁ¶°¡ ÀϾÁö ¾Ê½À´Ï´Ù.

# Äõ¿ìÆÃÀÇ Á¾·ù¿¡ µû¶ó ´Þ¶óÁö´Â °á°ú¿¡ ÁÖ¸ñÇϼ¼¿ä.


hello=    # ³Î °ªÀ» °®µµ·Ï ¼¼ÆÃ.
echo "\$hello (³Î °ª) = $hello"
#  º¯¼ö¸¦ ³Î °ªÀ¸·Î ¼¼ÆÃÇÏ´Â °Í°ú unset ÇÏ´Â °ÍÀº ºñ·Ï °á°ú´Â °°Áö¸¸
#+ ¾ö¿¬È÷ ´Ù¸¨´Ï´Ù(´ÙÀ½ ÂüÁ¶).

# --------------------------------------------------------------

#  ¿©·¯ º¯¼öµéÀ» °ø¹é¹®ÀÚ·Î ±¸ºÐÇؼ­ ÇÑ ÁÙ¿¡¼­ ¼¼Æ®ÇÒ ¼ö ÀÖ½À´Ï´Ù.
#  ÇÏÁö¸¸ ÀÌ·¸°Ô Çϸé ÄÚµåÀÇ °¡µ¶¼ºÀÌ ¶³¾îÁö°í 
#+ ´Ù¸¥ ½Ã½ºÅÛÀ¸·Î À̽ÄÇÒ ¼ö°¡ ¾øÀ» ¼öµµ Àֱ⠶§¹®¿¡ Á¶½ÉÇؼ­ ½á¾ß µË´Ï´Ù.

var1=variable1  var2=variable2  var3=variable3
echo
echo "var1=$var1   var2=$var2  var3=$var3"

# ¿¹Àü ¹öÀüÀÇ "sh"¿¡¼­´Â ¹®Á¦°¡ »ý±æ¼öµµ ÀÖ½À´Ï´Ù.

# --------------------------------------------------------------

echo; echo

numbers="one two three"
other_numbers="1 2 3"
# º¯¼ö¿¡ °ø¹é¹®ÀÚ°¡ µé¾î ÀÖ´Ù¸é Äõ¿ìÆÃÀ» ÇØÁà¾ß ÇÕ´Ï´Ù.
echo "numbers = $numbers"
echo "other_numbers = $other_numbers"
echo

echo "uninitialized_variable = $uninitialized_variable"
# ÃʱâÈ­ ¾È µÈ º¯¼ö´Â ³Î °ªÀ» °®½À´Ï´Ù(¾Æ¹« °ªµµ ¾ø½À´Ï´Ù).
uninitialized_variable=   #  ¼±¾ð¸¸ ÇÏ°í ÃʱâÈ­ ¾ÈÇÔ.
                          #+ (À§¿¡¼­Ã³·³ ³Î °ªÀ¸·Î ¼¼ÆÃÇÑ °Í°ú ¶È°°À½).
echo "uninitialized_variable = $uninitialized_variable"
                          # ¿©ÀüÈ÷ ³Î °ªÀ» °®°í Àֳ׿ä.

uninitialized_variable=23       # ¼¼Æ®.
unset uninitialized_variable    # ¾ð¼¼Æ®.
echo "uninitialized_variable = $uninitialized_variable"
                                # ¿©ÀüÈ÷ ³Î °ªÀÔ´Ï´Ù.

echo

exit 0