Master Linux Process & User Queries with Powerful Bash Scripts

1. Retrieve all information for a given PID

<code>#! /bin/bash
# Function: Filter all information of the entered PID
read -p "请输入要查询的PID: " P
n=`ps -aux| awk '$2~/^'$P'$/ {print $11}'|wc -l`
if [ $n -eq 0 ]; then
  echo "该PID不存在！！"
  exit
fi
echo "--------------------------------"
echo "进程PID: $P"
echo "进程命令：`ps -aux| awk '$2~/^'$P'$/ {print $11}'`"
echo "进程所属用户: `ps -aux| awk '$2~/^'$P'$/ {print $1}'`"
echo "CPU占用率：`ps -aux| awk '$2~/^'$P'$/ {print $3}'`%"
echo "内存占用率：`ps -aux| awk '$2~/^'$P'$/ {print $4}'`%"
echo "进程开始运行的时刻：`ps -aux| awk '$2~/^'$P'$/ {print $9}'`"
echo "进程运行的时间：`ps -aux| awk '$2~/^'$P'$/ {print $10}'`"
echo "进程状态：`ps -aux| awk '$2~/^'$P'$/ {print $8}'`"
echo "进程虚拟内存：`ps -aux| awk '$2~/^'$P'$/ {print $5}'`"
echo "进程共享内存：`ps -aux| awk '$2~/^'$P'$/ {print $6}'`"
echo "--------------------------------"
</code>

2. Retrieve process information by process name

<code>#! /bin/bash
# Function: Filter PIDs and details for a given process name
read -p "请输入要查询的进程名：" NAME
N=`ps -aux | grep $NAME | grep -v grep | wc -l`  ##统计进程总数
if [ $N -le 0 ]; then
  echo "该进程名没有运行！"
  fi
i=1
while [ $N -gt 0 ]
do
  echo "进程PID: `ps -aux | grep $NAME | grep -v grep | awk 'NR=='$i'{print $0}'| awk '{print $2}'`"
  echo "进程命令：`ps -aux | grep $NAME | grep -v grep | awk 'NR=='$i'{print $0}'| awk '{print $11}'`"
  echo "进程所属用户: `ps -aux | grep $NAME | grep -v grep | awk 'NR=='$i'{print $0}'| awk '{print $1}'`"
  echo "CPU占用率：`ps -aux | grep $NAME | grep -v grep | awk 'NR=='$i'{print $0}'| awk '{print $3}'`%"
  echo "内存占用率：`ps -aux | grep $NAME | grep -v grep | awk 'NR=='$i'{print $0}'| awk '{print $4}'`%"
  echo "进程开始运行的时刻：`ps -aux | grep $NAME | grep -v grep | awk 'NR=='$i'{print $0}'| awk '{print $9}'`"
  echo "进程运行的时间：`ps -aux | grep $NAME | grep -v grep | awk 'NR=='$i'{print $0}'| awk '{print $11}'`"
  echo "进程状态：`ps -aux | grep $NAME | grep -v grep | awk 'NR=='$i'{print $0}'| awk '{print $8}'`"
  echo "进程虚拟内存：`ps -aux | grep $NAME | grep -v grep | awk 'NR=='$i'{print $0}'| awk '{print $5}'`"
  echo "进程共享内存：`ps -aux | grep $NAME | grep -v grep | awk 'NR=='$i'{print $0}'| awk '{print $6}'`"
  echo "***************************************************************"
  let N-- i++
done
</code>

3. Query all information for a given username

<code>#! /bin/bash
# Function: Retrieve all information of a user by username
read -p "请输入要查询的用户名：" A
echo "------------------------------"
n=`cat /etc/passwd | awk -F: '$1~/^'$A'$/ {print}' | wc -l`
if [ $n -eq 0 ]; then
  echo "该用户不存在"
  echo "------------------------------"
else
  echo "该用户的用户名：$A"
  echo "该用户的UID：`cat /etc/passwd | awk -F: '$1~/^'$A'$/ {print}'|awk -F: '{print $3}'`"
  echo "该用户的组为：`id $A | awk '{print $3}'`"
  echo "该用户的GID为：`cat /etc/passwd | awk -F: '$1~/^'$A'$/ {print}'|awk -F: '{print $4}'`"
  echo "该用户的家目录为：`cat /etc/passwd | awk -F: '$1~/^'$A'$/ {print}'|awk -F: '{print $6}'`"
  Login=`cat /etc/passwd | awk -F: '$1~/^'$A'$/ {print}'|awk -F: '{print $7}'`
  if [ $Login == "/bin/bash" ]; then
    echo "该用户有登录系统的权限！！"
    echo "------------------------------"
  elif [ $Login == "/sbin/nologin" ]; then
    echo "该用户没有登录系统的权限！！"
    echo "------------------------------"
  fi
fi
</code>

4. System hardening configurations

<code>#! /bin/bash
# Function: Strengthen password policies and other security settings
read -p "设置密码最多可多少天不修改：" A
read -p "设置密码修改之间最小的天数：" B
read -p "设置密码最短的长度：" C
read -p "设置密码失效前多少天通知用户：" D
sed -i '/^PASS_MAX_DAYS/c\PASS_MAX_DAYS '$A'' /etc/login.defs
sed -i '/^PASS_MIN_DAYS/c\PASS_MIN_DAYS '$B'' /etc/login.defs
sed -i '/^PASS_MIN_LEN/c\PASS_MIN_LEN '$C'' /etc/login.defs
sed -i '/^PASS_WARN_AGE/c\PASS_WARN_AGE '$D'' /etc/login.defs

echo "已对密码进行加固，新用户不得和旧密码相同，且新密码必须同时包含数字、小写字母，大写字母！！"
sed -i '/pam_pwquality.so/c\password requisite pam_pwquality.so try_first_pass local_users_only retry=3 authtok_type= difok=1 minlen=8 ucredit=-1 lcredit=-1 dcredit=-1' /etc/pam.d/system-auth

echo "已对密码进行加固，如果输入错误密码超过3次，则锁定账户！！"
n=`cat /etc/pam.d/sshd | grep "auth required pam_tally2.so "|wc -l`
if [ $n -eq 0 ]; then
  sed -i '/%PAM-1.0/a\auth required pam_tally2.so deny=3 unlock_time=150 even_deny_root root_unlock_time300' /etc/pam.d/sshd
fi

echo "已设置禁止root用户远程登录！！"
sed -i '/PermitRootLogin/c\PermitRootLogin no'  /etc/ssh/sshd_config

read -p "设置历史命令保存条数：" E
read -p "设置账户自动注销时间：" F
sed -i '/^HISTSIZE/c\HISTSIZE='$E'' /etc/profile
sed -i '/^HISTSIZE/a\TMOUT='$F'' /etc/profile

echo "已设置只允许wheel组的用户可以使用su命令切换到root用户！"
sed -i '/pam_wheel.so use_uid/c\auth required pam_wheel.so use_uid ' /etc/pam.d/su
n=`cat /etc/login.defs | grep SU_WHEEL_ONLY | wc -l`
if [ $n -eq 0 ]; then
  echo "SU_WHEEL_ONLY yes" >> /etc/login.defs
fi

echo "即将对系统中的账户进行检查...."
echo "系统中有登录权限的用户有："
awk -F: '($7=="/bin/bash"){print $1}' /etc/passwd
echo "********************************************"
echo "系统中UID=0的用户有："
awk -F: '($3=="0"){print $1}' /etc/passwd
echo "********************************************"
N=`awk -F: '($2==""){print $1}' /etc/shadow|wc -l`
echo "系统中空密码用户有：$N"
if [ $N -eq 0 ]; then
  echo "恭喜你，系统中无空密码用户！！"
  echo "********************************************"
else
  i=1
  while [ $N -gt 0 ]
  do
    None=`awk -F: '($2==""){print $1}' /etc/shadow|awk 'NR=='$i'{print}'`
    echo "------------------------"
    echo $None
    echo "必须为空用户设置密码！！"
    passwd $None
    let N--
  done
  M=`awk -F: '($2==""){print $1}' /etc/shadow|wc -l`
  if [ $M -eq 0 ]; then
    echo "恭喜，系统中已经没有空密码用户了！"
  else
    echo "系统中还存在空密码用户：$M"
  fi
fi

echo "即将对系统中重要文件进行锁定，锁定后将无法添加删除用户和组"
read -p "警告：此脚本运行后将无法添加删除用户和组！！确定输入Y，取消输入N；Y/N：" i
case $i in
  [Yy])
    chattr +i /etc/passwd
    chattr +i /etc/shadow
    chattr +i /etc/group
    chattr +i /etc/gshadow
    echo "锁定成功！"
    ;;
  [Nn])
    chattr -i /etc/passwd
    chattr -i /etc/shadow
    chattr -i /etc/group
    chattr -i /etc/gshadow
    echo "取消锁定成功！！"
    ;;
  *)
    echo "请输入Y/y or N/n"
    ;;
esac
</code>