#!/bin/bash
# 5°¡ÁöÀÇ ´Ù¸¥ ¹æ¹ýÀ¸·Î 6±îÁö ¼¼±â.

n=1; echo -n "$n "

let "n = $n + 1"   # let "n = n + 1"   À̶ó°í Çصµ µË´Ï´Ù.
echo -n "$n "

: $((n = $n + 1))
#  ":" °¡ ¾øÀ¸¸é Bash°¡ "$((n = $n + 1))"À» 
#+ ¸í·É¾î·Î Çؼ®ÇÏ·Á°í Çϱ⠶§¹®¿¡ ÇÊ¿äÇÕ´Ï´Ù.
echo -n "$n "

n=$(($n + 1))
echo -n "$n "

: $[ n = $n + 1 ]
#  ":" °¡ ¾øÀ¸¸é Bash°¡ "$[n = $n + 1]"À» 
#+ ¸í·É¾î·Î Çؼ®ÇÏ·Á°í Çϱ⠶§¹®¿¡ ÇÊ¿äÇÕ´Ï´Ù.
#  "n"ÀÌ ¹®ÀÚ¿­·Î ÃʱâÈ­ µÇ¾î À־ µ¿ÀÛÇÕ´Ï´Ù.
echo -n "$n "

n=$[ $n + 1 ]
#  "n"ÀÌ ¹®ÀÚ¿­·Î ÃʱâÈ­ µÇ¾î À־ µ¿ÀÛÇÕ´Ï´Ù.
#* ÀÌ·± ÇüÅ´ ´õ ÀÌ»ó Áö¿øµÇÁö ¾Ê°í À̽ļºµµ ¾ø±â ¶§¹®¿¡ ¾²Áö ¸¶¼¼¿ä.
echo -n "$n "; echo

# Thanks, Stephane Chazelas.

exit 0