#!/bin/bash

# /etc/passwd ¸¦ º¸°í »ç¿ëÀÚ °èÁ¤À̸§¿¡¼­ "½ÇÁ¦ À̸§"À» ¾Ë¾Æ³¿.

ARGCOUNT=1  # ÇÑ °³ ÀÎÀÚ¸¸ ÇÊ¿ä.
E_WRONGARGS=65

file=/etc/passwd
pattern=$1

if [ $# -ne "$ARGCOUNT" ]
then
  echo "»ç¿ë¹ý: `basename $0` USERNAME"
  exit $E_WRONGARGS
fi  

file_excerpt ()  # ÆÄÀÏ¿¡¼­ ÆÐÅÏÀ» °Ë»öÇؼ­ ÇØ´ç ºÎºÐÀ» Ãâ·Â.
{
while read line  # while ¿¡¼­ ²À "[ condition ]" À» ¾È ½áµµ µË´Ï´Ù.
do
  echo "$line" | grep $1 | awk -F":" '{ print $5 }'  # awk °¡ ":" ±¸ºÐÀÚ¸¦ ¾²µµ·Ï.
done
} <$file  # ÇÔ¼ö Ç¥ÁØÀÔ·ÂÀ¸·Î ÀçÁöÇâ.

file_excerpt $pattern

# ÀÌ Àüü ½ºÅ©¸³Æ®´Â ´ÙÀ½Ã³·³ Çصµ µË´Ï´Ù.
#       grep PATTERN /etc/passwd | awk -F":" '{ print $5 }'
# ¾Æ´Ï¸é
#       awk -F: '/PATTERN/ {print $5}'
# ȤÀº
#       awk -F: '($1 == "username") { print $5 }' # »ç¿ëÀÚ À̸§À» º¸°í ½ÇÁ¦À̸§À» ã¾Æ³¿
# ÇÏÁö¸¸, ÀÌ·± ¹æ¹ýÀº ±³À°ÀûÀÌÁö´Â ¾ÊÀº °Í °°³×¿ä.

exit 0