shell第三章 shell脚本的基础知识

脚本中命令的解释器

        1.记录命令执行的过程和执行逻辑,以便以后重复执行
        2.脚本可以批量处理主机
        3.脚本可以定时处理主机

#!/bin/bash        ##幻数

vim自动添加脚本首部:

vim ~/.vimrc

set nu ts=2 et ai

"map ms:call WESTOSSHELL()'s    ##按F4时出现， “ 表注释
autocmd BufNewFile *.sh,.script call WESTOSSHELL()  ##当建立以.sh或者.script结尾的新的文件时，自动调用WESTOSHELL
func WESTOSSHELL()
        call append(0,"############################")
        call append(1,"# Author:           ")
        call append(2,"# Version:          ")
        call append(3,"#Create_Time: ".strftime("%Y-%m-%d"))
        call append(4,"#Mail: ")
        call append(5,"#Info: ")
        call append(6,"# ")
        call append(7,"##############################")
        call append(8,"")
        call append(9,"#!/bin/bash")
endfunc

sh test.sh

source script.sh
. script.sh

chmod +x script.sh
/xxx/xxx/script.sh
./script.sh

sh -x /mnt/westos.sh
+              ##运行指令
不带+        ##命令运行的输出

练习脚本1：
ip_show.sh 网卡               ##显示当前的IP

vim ip_show.sh

#!/bin/bash
[ -z "$1" ] &&{
   echo "PLease input "
   exit
}

DEV_MESSAGE=$(ifconfig "$1"  2> /dev/null ) &&{
    echo $DEV_MESSAGE | awk  '/inet>/{print $6}'

} ||{
    echo "$1 is not exist!!"
}

练习脚本2：
host_messages.sh 显示当前主机的名称,ip登陆当前主机的用户
hostname:  xxxxx
ipaddress:  xxxx.xxxx.xxx.xxx
username:  root

#!/bin/bash
echo -e "hostname:t$HOSTNAME"
echo "ipaddress:      `ifconfig ens3 | awk '/inet>/{print $2}'`"
echo -e "username: t $USER"
[root@westoslinux mnt]# sh host_messages.sh 
hostname:	westoslinux.westos.org
ipaddress:      172.25.254.110
username: 	 root

当网卡不止一个时：

vim host_messages.sh 
#!/bin/bash
echo -e "hostname:t$HOSTNAME"
for NETDEV in `awk -F : '/:/&&!/lo/{print $1}' /proc/net/dev `
do
  echo -e "ipaddress:       ` ifconfig $NETDEV | awk '/inet>/{print $2}'`"
done
echo -e "username: t $USER"

练习脚本3：
clear_log.sh          ##执行此脚本后可以清空日志

sed -n $= /etc/rsyslog.conf  ##显示/etc/rsyslog.conf最后一行的行号
grep -A `sed -n $= /etc/rsyslog.conf` RULES /etc/rsyslog.conf ## 显示/etc/rsyslog.conf中RULES后的79行
awk '!/^#|^$|:/{print $2}'| sed 's/-//g'  ##除了以#开头和空行之外的显示第二列，将-替换为空

从配置文件中获取日志的具体存放路径：
grep -A `sed -n $= /etc/rsyslog.conf` RULES /etc/rsyslog.conf | awk '!/^#|^$|:/{print $2}'| sed 's/-//g'

vim clear_log.sh 

#!/bin/bash
[ "$USER" != "root" ] &&{
  echo "Please run $0 with root!!"   ##判断是否为超级用户身份运行此脚本
  exit
}
for MESSAGES_FILE in `grep -A $(sed -n $= /etc/rsyslog.conf) RULES /etc/rsyslog.conf | awk '!/^#|^$|:/{print $2}'| sed 's/-//g'`
do
>$MESSAGES_FILE
done