[root@m01 /server/scripts]# oldboy=I love you
-bash: love: command not found
[root@m01 /server/scripts]# echo $oldboy

[root@m01 /server/scripts]# oldboy='I love you'
[root@m01 /server/scripts]# echo $oldboy
I love you

[root@m01 /server/scripts]# env |grep OLDBOY
[root@m01 /server/scripts]# OLDBOY=oldboyedu.com
[root@m01 /server/scripts]# env |grep OLDBOY
[root@m01 /server/scripts]# echo OLDBOY
lidaoav.com
[root@m01 /server/scripts]# env |grep OLDBOY
OLDBOY=lidaoav.com

局部变量VS全局变量

[root@m01 /server/scripts]# LIDAO=996
[root@m01 /server/scripts]#
[root@m01 /server/scripts]# echo $LIDAO
996
[root@m01 /server/scripts]# cat show.sh

!/bin/bash

echo $LIDAO

https://www.processon.com/view/link/5a0e4380e4b06c8e10923353
-export含义 局部与全局区别

awk中引用变量
[root@m01 /server/scripts]# x=10
[root@m01 /server/scripts]# y=99
[root@m01 /server/scripts]# awk 'BEGIN{print y}'
awk: cmd. line:1: fatal: division by zero attempted
[root@m01 /server/scripts]# awk 'BEGIN{print x,y}'

[root@m01 /server/scripts]# awk -vn1=10 -vn2=99 'BEGIN{print n1/n2}'
0.10101
[root@m01 /server/scripts]# awk -vn1=y 'BEGIN{print n1/n2}'
0.10101
awk
-v 命令行与awk桥梁

[root@m01 /server/scripts]# cat  cal.sh 
#!/bin/bash

x=$1
y=$2

awk -vn1=$x -vn2=$y  'BEGIN{print n1/n2}'
awk -vn1=$x -vn2=$y  'BEGIN{print n1*n2}'
awk -vn1=$x -vn2=$y  'BEGIN{print n1-n2}'
awk -vn1=$x -vn2=$y  'BEGIN{print n1+n2}'

[root@m01 /server/scripts]# sh cal.sh  1 3
0.333333
3
-2
4
[root@m01 /server/scripts]# 

[root@m01 /server/scripts]# [ -d /tmp/oldboyabc ]  && echo dir exist
[root@m01 /server/scripts]# [ -d /tmp/oldboyabc ]  || mkdir -p /tmp/oldboyabc 
[root@m01 /server/scripts]# ll -d /tmp/oldboyabc/
drwxr-xr-x 2 root root 6 May 30 10:37 /tmp/oldboyabc/

if [ 年薪1000000000w ];then
迎娶白富美
fi 


如果 [ 年薪1000000000w ];然后
 迎娶白富美
 迎娶白富美
果如 

#!/bin/bash

x=$1
y=$2
if [ 参数个数不是2 ];then
   echo "Usage: sh $0 num1 num2 "
fi

awk -vn1=$x -vn2=$y  'BEGIN{print n1/n2}'
awk -vn1=$x -vn2=$y  'BEGIN{print n1*n2}'
awk -vn1=$x -vn2=$y  'BEGIN{print n1-n2}'
awk -vn1=$x -vn2=$y  'BEGIN{print n1+n2}'

[root@m01 /server/scripts]# cat  cal-v2.sh 
#!/bin/bash

x=$1
y=$2
if [ $# -ne 2 ];then
   echo "Usage: sh $0 num1 num2 "
   exit
fi

awk -vn1=$x -vn2=$y  'BEGIN{print n1/n2}'
awk -vn1=$x -vn2=$y  'BEGIN{print n1*n2}'
awk -vn1=$x -vn2=$y  'BEGIN{print n1-n2}'
awk -vn1=$x -vn2=$y  'BEGIN{print n1+n2}'

if [ guoav 是高富帅 ];then 
   迎娶傻白甜 
else 
   抠脚大汉 caiav 
fi 

书写脚本comp.sh 比较两个数字的大小 
a >  b 显示 a > b 
a 不> b 显示 a <= b 

a   b  
  >
  <
  == 

[root@m01 /server/scripts]# cat comp.sh

!/bin/bash

a=2

if [ 0 num1 num2 "
exit
fi

if [ b ];then
echo "b"
else
echo "b"
fi

[root@m01 /server/scripts]# sh comp.sh  10 20 
[root@m01 /server/scripts]# sh comp.sh  10 20 
10 less equal 20
[root@m01 /server/scripts]# sh comp.sh  10 
Usage: sh comp.sh num1 num2 
[root@m01 /server/scripts]# sh comp.sh  
Usage: sh comp.sh num1 num2 

[root@m01 /server/scripts]# cat comp-multi.sh

!/bin/bash

a=2

if [ 0 num1 num2 "
exit
fi

if [ b ];then
echo "b"
elif [ b ];then
echo "b"
else
echo "b"
fi

[root@m01 /server/scripts]#
[root@m01 /server/scripts]# sh comp-multi.sh 10 20
10 < 20
[root@m01 /server/scripts]# sh comp-multi.sh 20 1
20 > 1
[root@m01 /server/scripts]# sh comp-multi.sh 2 2
2 == 2

count=ps -ef |grep crond |wc -l

if [ 如果进程数等于 2 ];then
定时任务运行中
else
定时任务挂了
fi

[root@m01 /server/scripts]# cat check.sh

!/bin/bash

count=ps -ef |grep crond |grep -v grep |wc -l
if [ $count -eq 1 ];then
echo "crond is running"
else
echo "crond is guale"
fi

[root@m01 /server/scripts]# ps -ef |grep  '[c]rond'
root      16542      1  0 12:04 ?        00:00:00 /usr/sbin/crond -n
执行进程名称是 ps -ef |grep  '[c]rond'
进程运行   ps -ef |grep  'crond'
避免个过滤的时候 过滤grep命令自己

[root@m01 /server/scripts]# ps -ef |grep -c '[c]rond'
1



week01 带思远去找 girl01 大宝剑
week02 带思远去找 girl02 大宝剑
week03 带思远去找 girl03 大宝剑
week04 带思远去找 girl04 大宝剑
week05 带思远去找 girl05 大宝剑
week06 带思远去找 girl06 大宝剑
week07 带思远去找 girl07 大宝剑

for n  in {01..7}
do 
    echo week$n 带思远去找 girl$n 大宝剑

done