7 Essential Everyday Shell Scripts for Linux System Administration

1. list_sys_status.sh – Display basic system network information

This script prints the host name, IP address, subnet mask, gateway, and DNS server of the machine by parsing ifconfig and /etc/resolv.conf, then echoes each value with a Chinese label.

#!/bin/bash
IP=`ifconfig eth0 | head -2 | tail -1 | awk '{print $2}' | awk -F":" '{print $2}'`
ZW=`ifconfig eth0 | head -2 | tail -1 | awk '{print $3}' | awk -F":" '{print $2}'`
GW=`route -n | tail -1 | awk '{print $2}'`
HN=`hostname`
DNS=`head -1 /etc/resolv.conf | awk '{print $2}'`
echo '此机IP地址是' $IP
echo '此机子网掩码是' $ZW
echo '此机网关是' $GW
echo '此机主机名是' $HN
echo '此机DNS是' $DNS

2. mysqlbak.sh – Backup MySQL data directory

The script records the current date and the size of /var/lib/mysql, writes this information to /tmp/dbinfo.txt, creates a tar.gz archive of the MySQL directory together with the info file, and schedules itself via crontab to run every three hours.

#!/bin/bash
DAY=`date +%Y%m%d`
SIZE=`du -sh /var/lib/mysql`
echo "Date: $DAY" >> /tmp/dbinfo.txt
echo "Data Size: $SIZE" >> /tmp/dbinfo.txt
cd /opt/dbbak &>/dev/null || mkdir /opt/dbbak
tar zcf /opt/dbbak/mysqlbak-${DAY}.tar.gz /var/lib/mysql /tmp/dbinfo.txt &>/dev/null
rm -f /tmp/dbinfo.txt
crontab -e
55 23 */3 * * /opt/dbbak/dbbak.sh

3. Weekly full backup of the webdb database

Scheduled at 23:30 every Sunday, this script dumps the webdb database to /mysqlbak with a date‑based filename, flushes MySQL logs, archives the binary logs, and stores them in /mysqlbinlog.tar.gz.

#!/bin/bash
day=`date +%F`
mysqldump -hlocalhost -uroot -p123 webdb > /mysqlbak/webdb-${day}.sql
mysql -hlocalhost -uroot -p -e "flush logs"
tar zcf /mysqlbinlog.tar.gz /var/lib/mysql/mysqld-bin.0*
# crontab entry: 30 23 * * 7 /shell/webdb.sh

4. very.ser.sh – Check the status of a specific service

The script accepts a service name (limited to vsftpd, httpd, sshd, crond, mysqld), verifies whether it is running, prints "service is running" or starts the service if it is stopped. Two implementations are provided: one using read and another using positional parameters.

#!/bin/bash
read -p "请输入你的服务名:" service
if [ $service != 'crond' -a $service != 'httpd' -a $service != 'sshd' -a $service != 'mysqld' -a $service != 'vsftpd' ]; then
  echo "只能够检查'vsftpd,httpd,crond,mysqld,sshd'"
  exit 5
fi
service $service status &>/dev/null
if [ $? -eq 0 ]; then
  echo "服务在线"
else
  service $service start
fi

if [ -z $1 ]; then
  echo "You must specify a servername!"
  echo "Usage: `basename $0` servername"
  exit 2
fi
if [ $1 == "crond" ] || [ $1 == "mysql" ] || [ $1 == "sshd" ] || [ $1 == "httpd" ] || [ $1 == "vsftpd" ]; then
  service $1 status &>/dev/null
  if [ $? -eq 0 ]; then
    echo "$1 is running"
  else
    service $1 start
  fi
else
  echo "Usage:`basename $0` server name"
  echo "But only check for vsftpd httpd sshd crond mysqld" && exit 2
fi

5. pc_noline.sh – List online hosts in a subnet

This script pings IPs in the 192.168.1.10‑12 range, prints the addresses of reachable hosts, counts unreachable hosts, and logs the IPs and timestamps of failures to /tmp/ip.txt.

#!/bin/bash
ip=192.168.1.
j=0
for i in `seq 10 12`
do
  ping -c 3 $ip$i &>/dev/null
  if [ $? -eq 0 ]; then
    echo "在线的主机有：$ip$i"
  else
    let j++
    echo $ip$i >> /tmp/ip.txt
    date >> /tmp/ip.txt
  fi
done
echo "不在线的主机台数有 $j"

6. Simple forum password‑reset script

Interactive script that asks for the website directory, database credentials, and a username, then verifies the user exists in the forum’s MySQL table, prompts for a new password, hashes it with openssl md5, updates the password field, and flushes privileges.

#!/bin/bash
End=ucenter_members
MYsql=/home/lnmp/mysql/bin/mysql
read -p "Enter a website directory : " webdir
WebPath=/home/WebSer/$webdir/config
read -p "Enter dbuser name : " dbuser
read -sp "Enter dbuser password : " dbpass
read -p "Enter db name : " dbname
read -p "Enter db tablepre : " dbtablepre
Globalphp=`grep "tablepre*" $WebPath/config_global.php |cut -d "'" -f8`
Ucenterphp=`grep "UC_DBTABLEPRE*" $WebPath/config_ucenter.php |cut -d '.' -f2 | awk -F "'" '{print $1}'`
if [ $dbtablepre == $Globalphp ] && [ $dbtablepre == $Ucenterphp ]; then
  Start=$dbtablepre
  Pre=`echo $Start$End`
  read -p "Enter you name : " userset
  Result=`$MYsql -u$dbuser -p$dbpass $dbname -e "select username from $Pre where username='$userset'\G" | cut -d ' ' -f2 | tail -1`
  if [ $userset == $Result ]; then
    read -p "Enter your password : " userpass
    passnew=`echo -n $userpass | openssl md5 | cut -d ' ' -f2`
    $MYsql -u$dbuser -p$dbpass $dbname -e "update $Pre set password='$passnew' where username='$userset';"
    $MYsql -u$dbuser -p$dbpass $dbname -e "flush privileges;"
  else
    echo "$userset is not right user!"
    exit 1
  fi
else
  exit 2
fi

7. slave_status.sh – Verify MySQL master‑slave health

The script checks whether the MySQL service is running, whether the network to the master is reachable, whether a connection can be made with the provided credentials, and whether both Slave_IO_Running and Slave_SQL_Running flags are set to YES, reporting success or failure for each step.

#!/bin/bash
netstat -tulnp | grep :3306 &>/dev/null
if [ $? -eq 0 ]; then
  echo "服务正在运行"
else
  service mysqld start
fi
ping -c 3 192.168.1.100 &>/dev/null
if [ $? -eq 0 ]; then
  echo "网络连接正常"
else
  echo "网络连接失败"
fi
mysql -h192.168.1.100 -uroot -p123456 &>/dev/null
if [ $? -eq 0 ]; then
  echo "数据库连接成功"
else
  echo "数据库连接失败"
fi
IO=$(mysql -uroot -p123 -e "show slave status\G" | grep Slave_IO_Running | awk '{print $2}')
SQL=$(mysql -uroot -p123 -e "show slave status\G" | grep Slave_SQL_Running | awk '{print $2}')
if [ "$IO" == "Yes" ] && [ "$SQL" == "Yes" ]; then
  echo "IO and SQL 连接成功"
else
  echo "IO线程和SQL线程连接失败"
fi

These seven scripts provide a quick toolbox for routine Linux system administration tasks such as status reporting, data backup, service monitoring, network scanning, and MySQL maintenance.