#!/bin/bash

# Semestralni prace z predmetu 36UNX = Operacni system UNIX
# Michal Trs
# Zadani c.8  
# userdel

# Error codes
# 0 - success
# 1 - can't update password file
# 2 - bad command syntax
# 6 - specified user doesn't exist
# 8 - user currently logged in
# 10 - can't update group file
# 12 - can't remove home directory



# nastaveni promenych

del=0;
#ROOT="/cygdrive/c/skola/6.semestr/36unx/semestralka";


# nacist parametr
while getopts r volba
  do
    case $volba in
	    r)   del=1;;
	    \?)  exit 2;;
    esac
  done

shift `expr $OPTIND - 1`


# ulozit username + kontrola zda existuje
username=$1;
if ! grep ^$username: "$ROOT/etc/passwd" 1>/dev/null; then
  echo "specified user doesn't exist";
  exit 6;
fi


# kontrola zda neni user zalogovan....
if  who | grep "^${username}" >/dev/null; then
  echo "user currently logged in";
  exit 8;
fi


# pokud je zadan parametr -r smazat home
if [ $del -ne 0 ]; then 
  if ! rm -r `grep ^$username: "$ROOT/etc/passwd" | cut -d: -f6` 2>/dev/null; then
    echo "can't remove home directory";
    exit 12;
  fi
fi

# najit a odebrat ze souboru /etc/passwd a /etc/shadow uzivatele

if cp "$ROOT/etc/passwd" "$ROOT/etc/passwd-" 2>/dev/null; then 
  sed /^"$username:"/d "$ROOT/etc/passwd-" > "$ROOT/etc/passwd";
else
  echo "can't update password file"; 
  exit 1;
fi

if cp "$ROOT/etc/shadow" "$ROOT/etc/shadow-" 2>/dev/null; then
  sed /^"$username:"/d "$ROOT/etc/shadow-" > "$ROOT/etc/shadow";
fi

if cp "$ROOT/etc/group" "$ROOT/etc/group-" 2>/dev/null; then
  sed -e "s/:${username}$/:/" \
      -e "s/:${username},/:/" \
      -e "s/,${username}$//" \
      -e "s/,${username},/,/g" "$ROOT/etc/group-" > "$ROOT/etc/group";  
else  
  echo "can't update group file"; 
  exit 10;
fi