shell基础知识

if [ ! -d /home/upgrade/iaas_v331/conf_backups ]; then mkdir -p /home/upgrade/iaas_v331/conf_backups; fi

  cmd : [ -d /home/upgrade/iaas_v331/conf_backups/all ] || mkdir -p /home/upgrade/iaas_v331/conf_backups/all

                now=$(date +"%Y%m%d%H%M%S")

                tar -zcvf /home/upgrade/iaas_v331/conf_backups/all/etc_${now}.tar.gz /etc

if结构

if [ conidtion ] : then ... fi

if [ conditon ] : then ... else ... fi

if [ condition ] : then ... elif ... fi

简单的逻辑可以使用&& || 去替换

条件可以用命令返回值代替

if [ -e test ]; then echo exist; else echo not exist; fi

exist

[ -e test ]&&echo exist||echo not exist]

echo "1" && echo "2" || echo "3" && echo "4" || echo "5" ||echo "6" && echo "7" && echo "8" || echo "9"

1

2

4

7

8

for(( c1 : c2 : c3));

do

...;

done

for (( i=0; i<10; i++)); do echo $i; done

for x in ${array[@]}; do echo $x; done

for x in `ls`; do echo $x; done

while

i=0; while [ $i -lt 3 ];do echo $i; (( i=i+1 )); done

一个有用的小技巧，一行行的读取文件内容 while read line; do echo $line; done < /tmp/tmp

[root@zhouzz ~]# while read line; do echo $line;done < x

eeeee

fffff

ggggg

iiiii

ppppp

for f in *; do echo $f; if [ -f $f ]; then echo "this is file $f";else continue;fi;done;

bash 是一个进程 bash下还可以再重新启动一个shell，这个shell是sub shell，原shell复制自身给他

在sub shell中定义的变量，什随着sub shell的消失而消失

（）子shell中执行

{}当前shell中执行， $$当前脚本执行的pid

&后台执行

$! 运行在后台的最后一个作业的PID（进程ID）

a=100

~ � {a=1; echo $a;};echo $a;

1

1

echo $PATH |awk 'BEGIN{RS=":"}END{print NR}'

RS行记录分隔符

FS记录分隔符

NR记录数

NF字段数

BEGIN END

[root@zhouzz ~]# echo $PATH |awk 'BEGIN{RS=":"}{print $0}' |awk -F '/' '{print $1,$2,$3,$4}'

usr local sbin

usr local bin

usr sbin

usr bin

usr local java

usr local java

root bin

[root@zhouzz ~]# echo $PATH |awk 'BEGIN{RS=":"}{print $0}' |awk 'BEGIN{FS="/"}{print $1,$2,$3,$4}'

[root@zhouzz ~]# echo $PATH |awk 'BEGIN{RS=":"}{print $0}' |awk 'BEGIN{FS="/|-"}{print $1,$2,$3,$4}'

RS两行之间的分割符

FS 类同 -F ‘分割符’

sed

-e 多次操作

-i 替换原文

awk 'BEGIN{RS=":"}{print $0}' |sed 's#/#-----#g'

echo $PATH |awk 'BEGIN{RS=":"}{print $0}' |sed -n '/^/bin/./sbin/p'

sed -i -e ‘’ -e"

echo "2>1" |bc

类比SQL

grep 数据查找定位 =select * from table

awk数据切片 (名字来源于三个作者的名称) select field from table

sed数据修改

update table set field=new where field=old

grep -o pattern file 把每个匹配的内容用独立的行显示

grep -i pattern file忽略大小写

grep pattern -r dir / 递归搜索

grep -A -B -C pattern file 打印命中数据的上下文

echo "ABC" |grep -i abc

ps -ef |grep bash

ps -ef |grep bash |grep -v grep

[root@zhouzz ~]# echo "1234 7654" |grep "[0-9]4"

1234 7654

[root@zhouzz ~]# echo "1234 7654" |grep -o "[0-9]4"

34

54

patter:（BRE）

^,$

[0-9]

[a-z]

基本正则（BRE），扩展正则的区别ERE

*0个或多个

？非贪婪匹配

+一个或多个

（）分组

{}范围匹配

|匹配多个表达式的任何一个

[root@zhouzz ~]# echo "1234 7654" |grep -o "[0-9]4|76"

[root@zhouzz ~]# echo "1234 7654" |grep -oE "[0-9]4|76"

34

76

54

root@zhouzz tmp]# ls /tmp |grep jenkins83 -C2

hsperfdata_jenkins

hsperfdata_root

jenkins8376545221077029752.sh

systemd-private-40795f9ed6f04acdb904bee0520b03e8-mariadb.service-E8OrMz

systemd-private-40795f9ed6f04acdb904bee0520b03e8-ntpd.service-nzrdhO

[root@zhouzz tmp]# ls /tmp |grep jenkins83 -A2 -B2

hsperfdata_jenkins

hsperfdata_root

jenkins8376545221077029752.sh

systemd-private-40795f9ed6f04acdb904bee0520b03e8-mariadb.service-E8OrMz

systemd-private-40795f9ed6f04acdb904bee0520b03e8-ntpd.service-nzrdhO

grep 00:00:01 -r .

grep -E '404 | 503' /tmp/nginx.log |head -3

awk理论上可以代替grep

awk 'pattern{action}'

awk 'BEGIN{}END{}'开始与结束

awk '/Running/' 正则匹配

awk '/aa/,/bb/'区间匹配

awk 'NR==2' 取第二行

awk 'NR >1' 去掉第一行

ps | awk 'BEGIN{print "start"}{print $0}END{print "end"}'

awk '/ 404 | 500 /' /tmp/nginx.log

[root@zhouzz ~]# echo '1

> 2

> 3

> 4

> 5' |awk '/2/,/4/'

2

3

4

[root@zhouzz ~]# echo '1

> 2

> 3

> 4

> 5' |awk '$0>3'

4

5

echo '1

2

3

4

5' | awk '$0>3'

ps | awk 'NR>1'

ps | awk '{print $NF}'

echo $PATH | awk 'BEGIN{RS=":"}{print $0}' | grep -v "^$" | awk 'BEGIN{FS="
";ORS=":"}{print $0}END{printf "
" }'

echo '1,10

2,20

3,30' | awk 'BEGIN{a=0;FS=","}{a+=$2}END{print a,a/NR}'

awk 'BEGIN{print 33*20*76/200/3}'

echo "123|456_789" | awk 'BEGIN{FS="\||_"}{print $2}'

因为双引号存在，最外层单引号确保整个内容是原样传递给awk的。然后awk收到了双引号，双引号在awk内部也有转义，然后两个反斜杠变成了一个反斜杠。这样FS就会能正常的知道竖杠不是正则了。

echo "123|456_789" | awk "BEGIN{FS="\\||_"}{print $2}" #尽量使用单引号

[root@zhouzz ~]# echo '1,10

> 2,20

> 3,30' | awk 'BEGIN{a=0;FS=","}{a+=$2}END{print a,a/NR}'

60 20

grep -E " 404 | 500 " /tmp/nginx.log | awk '{print $9}' | sort | uniq -c

将单行分拆为多行

[root@zhouzz ~]# echo $PATH

/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/usr/local/java/jdk1.8/bin:/usr/local/java/jdk1.8/jre/bin:/root/bin

[root@zhouzz ~]# echo $PATH |awk 'BEGIN{RS=":"}{print $0}'

/usr/local/sbin

/usr/local/bin

/usr/sbin

/usr/bin

/usr/local/java/jdk1.8/bin

/usr/local/java/jdk1.8/jre/bin

/root/bin

[root@zhouzz ~]# echo $PATH |awk 'BEGIN{RS=":"}{print NR,$0}'

1 /usr/local/sbin

2 /usr/local/bin

3 /usr/sbin

4 /usr/bin

5 /usr/local/java/jdk1.8/bin

6 /usr/local/java/jdk1.8/jre/bin

7 /root/bin

[root@zhouzz ~]# echo $PATH |awk 'BEGIN{RS=":"}END{print NR}'

7

[root@zhouzz ~]# echo $PATH |awk 'BEGIN{RS=":"}END{print NR,$0}'

7 /root/bin

将多行合成一行

[root@zhouzz ~]# echo $PATH |awk 'BEGIN{RS=":"}{print $0}' |awk 'BEGIN{FS="
";ORS=":"}{print $0}'

/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/usr/local/java/jdk1.8/bin:/usr/local/java/jdk1.8/jre/bin:/root/bin::

[root@zhouzz ~]# echo $PATH |awk 'BEGIN{RS=":"}{print $0}' |awk 'BEGIN{FS="
";ORS=":"}{print $0}END{printf "
"}'

/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/usr/local/java/jdk1.8/bin:/usr/local/java/jdk1.8/jre/bin:/root/bin::

[root@zhouzz ~]# echo $PATH |awk 'BEGIN{RS=":"}{print $0}' |grep -v "^$"|awk 'BEGIN{FS="
";ORS=":"}{print $0}END{printf "
"}'

/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/usr/local/java/jdk1.8/bin:/usr/local/java/jdk1.8/jre/bin:/root/bin:

sed -n '2p' 打印第二行

sed 's#hello#world#'

-E 扩展表达式

--debug调试

ps | sed -n 1,3p

ps | sed 's/CMD/command/'

ps | sed -n '/ps/p'

echo '1

2

3

4

5' | sed -n '/3/,/4/p'

echo '1

2

3

4

5' | sed '/3/,/4/d'

ps | sed -e 's/CMD/command/' -e 's#00#20#g'

pattern表达式

action

[root@zhouzz ~]# echo '1

> 1

> 2

> 3

> 4

> 5

> 6' |sed -n '/3/,/4/p'

3

4

对所有404 500 的数据，统计出现这种状态码的url，需要对url汇总（汇总相似的url，把相同的资源但是变化的id去掉）去重，打印前5个出问题的路径，把命令贴到回复里