用bash shell写程序时,经常会用到for循环,特别是从1到100这种需求,这里记录几种shell中从1到100的循环方法
方法
类c语言
for ((i=1; i<=100; i ++))
do
echo $i
done
in使用
for i in {1..100}
do
echo $i
done
seq使用
作用
seq - print a sequence of numbers
代码
for i in `seq 1 100`
do
echo $i
done
30个经典shell
1、获取随机字符串或数字
获取随机8位字符串:
方法1:
echo $RANDOM |md5sum |cut -c 1-8
471b94f2
方法2:
openssl rand -base64 4
vg3BEg==
方法3:
cat /proc/sys/kernel/random/uuid |cut -c 1-8
ed9e032c
获取随机8位数字:
方法1:
echo $RANDOM |cksum |cut -c 1-8
23648321
方法2:
openssl rand -base64 4 |cksum |cut -c 1-8
38571131
方法3:
date +%N |cut -c 1-8
69024815
cksum:打印CRC效验和统计字节
2、定义一个颜色输出字符串函数
方法1:
function echo_color() {
if [ $1 == "green" ]; then
echo -e "33[32;40m$233[0m"
elif [ $1 == "red" ]; then
echo -e "33[31;40m$233[0m"
fi
}
方法2:
function echo_color() {
case $1 in
green)
echo -e "[32;40m$2[0m"
;;
red)
echo -e "[31;40m$2[0m"
;;
*)
echo "Example: echo_color red string"
esac
}
使用方法:echo_color green "test"
function关键字定义一个函数,可加或不加。
3、批量创建用户
!/bin/bash
DATE=$(date +%F_%T)
USER_FILE=user.txt
echo_color(){
if [ $1 == "green" ]; then
echo -e "[32;40m$2[0m"
elif [ $1 == "red" ]; then
echo -e "[31;40m$2[0m"
fi
}
如果用户文件存在并且大小大于0就备份
if [ -s $USER_FILE ]; then
mv $USER_FILE ${USER_FILE}-${DATE}.bak
echo_color green "$USER_FILE exist, rename ${USER_FILE}-${DATE}.bak"
fi
echo -e "User Password" >> $USER_FILE
echo "----------------" >> $USER_FILE
for USER in user{1..10}; do
if ! id $USER &>/dev/null; then
PASS=$(echo $RANDOM |md5sum |cut -c 1-8)
useradd $USER
echo $PASS |passwd --stdin $USER &>/dev/null
echo -e "$USER $PASS" >> $USER_FILE
echo "$USER User create successful."
else
echo_color red "$USER User already exists!"
fi
done
4、检查软件包是否安装
!/bin/bash
if rpm -q sysstat &>/dev/null; then
echo "sysstat is already installed."
else
echo "sysstat is not installed!"
fi
5、检查服务状态
!/bin/bash
PORT_C=$(ss -anu |grep -c 123)
PS_C=$(ps -ef |grep ntpd |grep -vc grep)
if [ $PORT_C -eq 0 -o $PS_C -eq 0 ]; then
echo "内容" | mail -s "主题" dst@example.com
fi
****
6、检查主机存活状态
方法1:将错误IP放到数组里面判断是否ping失败三次
!/bin/bash
IP_LIST="192.168.18.1 192.168.1.1 192.168.18.2"
for IP in $IP_LIST; do
NUM=1
while [ $NUM -le 3 ]; do
if ping -c 1 $IP > /dev/null; then
echo "$IP Ping is successful."
break
else
# echo "$IP Ping is failure $NUM"
FAIL_COUNT[$NUM]=$IP
let NUM++
fi
done
if [ ${#FAIL_COUNT[]} -eq 3 ];then
echo "${FAIL_COUNT[1]} Ping is failure!"
unset FAIL_COUNT[]
fi
done
方法2:将错误次数放到FAIL_COUNT变量里面判断是否ping失败三次
!/bin/bash
IP_LIST="192.168.18.1 192.168.1.1 192.168.18.2"
for IP in $IP_LIST; do
FAIL_COUNT=0
for ((i=1;i<=3;i++)); do
if ping -c 1 $IP >/dev/null; then
echo "$IP Ping is successful."
break
else
# echo "$IP Ping is failure $i"
let FAIL_COUNT++
fi
done
if [ $FAIL_COUNT -eq 3 ]; then
echo "$IP Ping is failure!"
fi
done
方法3:利用for循环将ping通就跳出循环继续,如果不跳出就会走到打印ping失败
!/bin/bash
ping_success_status() {
if ping -c 1 $IP >/dev/null; then
echo "$IP Ping is successful."
continue
fi
}
IP_LIST="192.168.18.1 192.168.1.1 192.168.18.2"
for IP in $IP_LIST; do
ping_success_status
ping_success_status
ping_success_status
echo "$IP Ping is failure!"
done
****
7、监控CPU、内存和硬盘利用率
1)CPU
借助vmstat工具来分析CPU统计信息。
!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=$(ifconfig eth0 |awk -F [ :]+ /inet addr/{print $4} ) # 只支持CentOS6
MAIL="example@mail.com"
if ! which vmstat &>/dev/null; then
echo "vmstat command no found, Please install procps package."
exit 1
fi
US=$(vmstat |awk NR==3{print $13} )
SY=$(vmstat |awk NR==3{print $14} )
IDLE=$(vmstat |awk NR==3{print $15} )
WAIT=$(vmstat |awk NR==3{print $16} )
USE=$(($US+$SY))
if [ $USE -ge 50 ]; then
echo "
Date: $DATE
Host: $IP
Problem: CPU utilization $USE
" | mail -s "CPU Monitor" $MAIL
fi
2)内存
!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=$(ifconfig eth0 |awk -F [ :]+ /inet addr/{print $4} )
MAIL="example@mail.com"
TOTAL=$(free -m |awk /Mem/{print $2} )
USE=$(free -m |awk /Mem/{print $3-$6-$7} )
FREE=$(($TOTAL-$USE))
内存小于1G发送报警邮件
if [ $FREE -lt 1024 ]; then
echo "
Date: $DATE
Host: $IP
Problem: Total=$TOTAL,Use=$USE,Free=$FREE
" | mail -s "Memory Monitor" $MAIL
fi
3)硬盘
!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=$(ifconfig eth0 |awk -F [ :]+ /inet addr/{print $4} )
MAIL="example@mail.com"
TOTAL=$(fdisk -l |awk -F [: ]+ BEGIN{OFS="="}/^Disk /dev/{printf "%s=%sG,",$2,$3} )
PART_USE=$(df -h |awk BEGIN{OFS="="}/^/dev/{print $1,int($5),$6} )
for i in $PART_USE; do
PART=$(echo $i |cut -d"=" -f1)
USE=$(echo $i |cut -d"=" -f2)
MOUNT=$(echo $i |cut -d"=" -f3)
if [ $USE -gt 80 ]; then
echo "
Date: $DATE
Host: $IP
Total: $TOTAL
Problem: $PART=$USE($MOUNT)
" | mail -s "Disk Monitor" $MAIL
fi
done
****
8、批量主机磁盘利用率监控
前提监控端和被监控端SSH免交互登录或者密钥登录。
写一个配置文件保存被监控主机SSH连接信息,文件内容格式:IP User Port
!/bin/bash
HOST_INFO=host.info
for IP in $(awk /^[^#]/{print $1} $HOST_INFO); do
USER=$(awk -v ip=$IP ip==$1{print $2} $HOST_INFO)
PORT=$(awk -v ip=$IP ip==$1{print $3} $HOST_INFO)
TMP_FILE=/tmp/disk.tmp
ssh -p $PORT $USER@$IP df -h > $TMP_FILE
USE_RATE_LIST=$(awk BEGIN{OFS="="}/^/dev/{print $1,int($5)} $TMP_FILE)
for USE_RATE in $USE_RATE_LIST; do
PART_NAME=${USE_RATE%=}
USE_RATE=${USE_RATE#=}
if [ $USE_RATE -ge 80 ]; then
echo "Warning: $PART_NAME Partition usage $USE_RATE%!"
fi
done
done
****
9、检查网站可用性
1)检查URL可用性
方法1:
check_url() {
HTTP_CODE=$(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}" $1)
if [ $HTTP_CODE -ne 200 ]; then
echo "Warning: $1 Access failure!"
fi
}
方法2:
check_url() {
if ! wget -T 10 --tries=1 --spider $1 >/dev/null 2>&1; then
-T超时时间,--tries尝试1次,--spider爬虫模式
echo "Warning: $1 Access failure!"
fi
}
使用方法:check_url www.baidu.com
2)判断三次URL可用性
思路与上面检查主机存活状态一样。
方法1:利用循环技巧,如果成功就跳出当前循环,否则执行到最后一行
!/bin/bash
check_url() {
HTTP_CODE=$(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}" $1)
if [ $HTTP_CODE -eq 200 ]; then
continue
fi
}
URL_LIST="www.baidu.com www.agasgf.com"
for URL in $URL_LIST; do
check_url $URL
check_url $URL
check_url $URL
echo "Warning: $URL Access failure!"
done
方法2:错误次数保存到变量
!/bin/bash
URL_LIST="www.baidu.com www.agasgf.com"
for URL in $URL_LIST; do
FAIL_COUNT=0
for ((i=1;i<=3;i++)); do
HTTP_CODE=$(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}" $URL)
if [ $HTTP_CODE -ne 200 ]; then
let FAIL_COUNT++
else
break
fi
done
if [ $FAIL_COUNT -eq 3 ]; then
echo "Warning: $URL Access failure!"
fi
done
方法3:错误次数保存到数组
!/bin/bash
URL_LIST="www.baidu.com www.agasgf.com"
for URL in $URL_LIST; do
NUM=1
while [ $NUM -le 3 ]; do
HTTP_CODE=$(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}" $URL)
if [ $HTTP_CODE -ne 200 ]; then
FAIL_COUNT[$NUM]=$IP #创建数组,以$NUM下标,$IP元素
let NUM++
else
break
fi
done
if [ ${#FAIL_COUNT[]} -eq 3 ]; then
echo "Warning: $URL Access failure!"
unset FAIL_COUNT[] #清空数组
fi
done
10、检查MySQL主从同步状态
!/bin/bash
USER=bak
PASSWD=123456
IO_SQLSTATUS=$(mysql -u$USER -p$PASSWD -e show slave statusG |awk -F: /Slave._Running/{gsub(": ",":");print $0} ) #gsub去除冒号后面的空格
for i in $IO_SQL_STATUS; do
THREAD_STATUS_NAME=${i%:}
THREAD_STATUS=${i#*:}
if [ "$THREAD_STATUS" != "Yes" ]; then
echo "Error: MySQL Master-Slave $THREAD_STATUS_NAME status is $THREAD_STATUS!"
fi
done
#删除temp文件的重复行
awk ‘!($0 in array) { array[$0]; print }’ temp
#查看最长使用的10个unix命令
awk ‘{print $1}’ ~/.bash_history | sort | uniq -c | sort -rn | head -n 10
#查看机器的ip列表
ifconfig -a | awk ‘/Bcast/{print $2}’ | cut -c 5-19
#查看机器的每个远程链接机器的连接数
netstat -antu | awk ‘$5 ~ /[0-9]:/{split($5, a, “:”); ips[a[1]]++} END {for (ip in ips) print ips[ip], ip | “sort -k1 -nr”}’
#查看某个进程打开的socket数量
ps aux | grep [process] | awk ‘{print $2}’ | xargs -I % ls /proc/%/fd | wc -l
#查看无线网络的ip
sudo ifconfig wlan0 | grep inet | awk ‘NR==1 {print $2}’ | cut -c 6-
#批量重命名文件
find . -name ‘*.jpg’ | awk ‘BEGIN{ a=0 }{ printf “mv %s name%01d.jpg\n”, $0, a++ }’ | bash
#查看某个用户打开的文件句柄列表
for x in `ps -u 500 u | grep java | awk ‘{ print $2 }’`;do ls /proc/$x/fd|wc -l;done
#计算文件temp的第一列的值的和
awk ‘{s+=$1}END{print s}’ temp
#查看最常用的命令和使用次数
history | awk ‘{if ($2 == “sudo”) a[$3]++; else a[$2]++}END{for(i in a){print a[i] ” ” i}}’ | sort -rn | head
#查找某个时间戳的文件列表
cp -p `ls -l | awk ‘/Apr 14/ {print $NF}’` /usr/users/backup_dir
#格式化输出当前的进程信息
ps -ef | awk -v OFS=”\n” ‘{ for (i=8;i<=NF;i++) line = (line ? line FS : "") $i; print NR ":", $1, $2, $7, line, ""; line = "" }' #查看输入数据的特定位置的单个字符 echo "abcdefg"|awk 'BEGIN {FS="''"} {print $2}' #打印行号 ls | awk '{print NR "\t" $0}' #打印当前的ssh 客户端 netstat -tn | awk '($4 ~ /:22\s*/) && ($6 ~ /^EST/) {print substr($5, 0, index($5,":"))}' #打印文件第一列不同值的行 awk '!array[$1]++' file.txt #打印第二列唯一值 awk '{ a[$2]++ } END { for (b in a) { print b } }' file #查看系统所有分区 awk '{if ($NF ~ "^[a-zA-Z].*[0-9]$" && $NF !~ "c[0-9]+d[0-9]+$" && $NF !~ "^loop.*") print "/dev/"$NF}' /proc/partitions #查看2到100所有质数 for num in `seq 2 100`;do if [ `factor $num|awk '{print $2}'` == $num ];then echo -n "$num ";fi done;echo #查看第3到第6行 awk 'NR >= 3 && NR <= 6' /path/to/file #逆序查看文件 awk '{a[i++]=$0} END {for (j=i-1; j>=0;) print a[j–] }’
#打印99乘法表
seq 9 | sed ‘H;g’ | awk -v RS=” ‘{for(i=1;i<=NF;i++)printf("%dx%d=%d%s", i, NR, i*NR, i==NR?"\n":"\t")}'