linux常用的shell脚本

一、检查系统负载：检查系统的负载情况，并在超过阈值时发送警报。可使用 uptime 命令和条件语句来实现

#!/bin/bash
    CPU_USAGE=$(top -bn1 | grep "Cpu(s)" | awk '{print $2 + $4}')THRESHOLD=80THRESHOLD=80if (( $(echo "$CPU_USAGE > $THRESHOLD" | bc -l) )); then
    echo"CPU usage is high: $CPU_USAGE%"
    # Send alert email or trigger automated responsefi

二、备份文件：编写一个脚本以定期备份指定目录的文件。可以使用 cp 命令和 cron 作业调度程序来完成

#!/bin/bash
backup_dir="/path/to/backup"
source_dir="/path/to/source"
timestamp=$(date +%Y%m%d%H%M%S)
backup_file="backup_$timestamp.tar.gz"
tar czf "$backup_dir/$backup_file" "$source_dir"

三、清理日志文件：编写一个脚本以清理旧的日志文件，保留最近的一段时间内的文件。可以使用 find 命令和条件语句来实现

#!/bin/bash
log_dir="/path/to/logs"
days_to_keep=7
find "$log_dir" -type f -name "*.log" -mtime +$days_to_keep -delete

四、监控服务状态：编写一个脚本以监控关键服务的运行状态，并在服务异常时发送警报。可以使用 systemctl 命令和条件语句来实现

#!/bin/bash
service_name="nginx"
if ! systemctl is-active --quiet "$service_name"; then
    echo "服务 $service_name 未运行" | mail -s "服务状态警报" [email protected]
fi

五、自动化部署：编写一个脚本以自动化部署应用程序或配置文件到多台服务器。可以使用 rsync 命令和循环结构来实现

#!/bin/bash
servers=("server1" "server2" "server3")
source_dir="/path/to/source"
destination_dir="/path/to/destination"
for server in "${servers[@]}"; do
    rsync -avz "$source_dir" "$server:$destination_dir"
done

六、监控磁盘空间：编写一个脚本以监控系统磁盘空间使用情况，并在空间不足时发送警报。可以使用 df 命令和条件语句来实现

#!/bin/bash
threshold=90
df_output=$(df -h)
while read -r line; do
    usage=$(echo "$line" | awk '{print $5}' | sed 's/%//')
    if (( usage > threshold )); then
        echo "磁盘空间不足: $line" | mail -s "磁盘空间警报" [email protected]
    fi
done <<< "$df_output"

七、启动/停止服务：编写一个脚本以同时启动或停止多个服务可以使用 systemctl 命令和循环结构来实现

#!/bin/bash
services=("service1" "service2" "service3")
action="start"  # 或者 "stop"
for service in "${services[@]}"; do
    systemctl "$action" "$service"
done

八、批量修改服务器用户密码

# cat old_pass.txt   
192.168.18.217  root    123456     22  
192.168.18.218  root    123456     22  
内容格式：IP User Password Port  

SSH远程修改密码脚本：新密码随机生成  
https://www.linuxprobe.com/books  
#!/bin/bash  
OLD_INFO=old_pass.txt  
NEW_INFO=new_pass.txt  
for IP in $(awk '/^[^#]/{print $1}' $OLD_INFO); do  
    USER=$(awk -v I=$IP 'I==$1{print $2}' $OLD_INFO)  
    PASS=$(awk -v I=$IP 'I==$1{print $3}' $OLD_INFO)  
    PORT=$(awk -v I=$IP 'I==$1{print $4}' $OLD_INFO)  
    NEW_PASS=$(mkpasswd -l 8)  # 随机密码  
    echo "$IP   $USER   $NEW_PASS   $PORT" >> $NEW_INFO  
    expect -c "  
    spawn ssh -p$PORT $USER@$IP  
    set timeout 2  
    expect {  
        \"(yes/no)\" {send \"yes\r\";exp_continue}  
        \"password:\" {send \"$PASS\r\";exp_continue}  
        \"$USER@*\" {send \"echo \'$NEW_PASS\' |passwd --stdin $USER\r exit\r\";exp_continue}  
    }"  
done  
生成新密码文件：

# cat new_pass.txt   
192.168.18.217  root    n8wX3mU%      22  
192.168.18.218  root    c87;ZnnL      22  

Linux主机SSH连接信息：旧密码

九、数据处理脚本

#!/bin/bash

DATA_FILE="data.csv"
OUTPUT_FILE="processed_data.csv"

# Remove header and extract specific columns
tail -n +2 "$DATA_FILE" | cut -d ',' -f 1,3 > "$OUTPUT_FILE"
echo "Data processing completed. Processed data saved to $OUTPUT_FILE"

十、自动化测试脚本

#!/bin/bash

TEST_URL="http://example.com"
EXPECTED_RESPONSE="200 OK"
TEST_RESULT=$(curl -s -o /dev/null -w "%{http_code}" $TEST_URL)

if [ "$TEST_RESULT" = "$EXPECTED_RESPONSE" ]; then
    echo "Test passed: HTTP status code is 200 OK"
else
    echo "Test failed: HTTP status code is not 200 OK"
fi

十一、日常维护脚本

#!/bin/bash

# Check disk space usage
df -h

# Check system load
uptime

# Check running processes
ps aux

# Check system logs for errors
tail /var/log/syslog | grep "error"

# Check for available software updates
apt update
apt list --upgradable

十二、性能优化脚本

#!/bin/bash

# Check CPU usage
top -b -n 1 | grep "Cpu(s)"

# Check memory usage
free -h

# Check disk I/O
iostat

# Check network usage
iftop

# Check for high load processes
ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%cpu