文本替换求助-变量定义替换

RE_HASH

$>  grep host my.def|sed  's/\(host.\)=\(.\+\)/s\/\1=.\\+\/\1=\2\//'|sed -f - my.profile
#! /bin/sh
# my.profile
host1=www.sina.com.cn
host3=www.baidu.com
host4=www.taobao.com
test_ping() { echo "$(ping -c 3 $1 |grep avg|cut -d "/" -f4|cut -d "." -f1)" ; }
for host in $host1 $host3 $host4; do echo "$host: $(test_ping $host)"; done

RE_HASH

回复 7# sunzhiguolu

深有同感

$>  grep host my.def|sed  's/\(host.\)=\(.\+\)/s\/\1=.\\+\/\1=\2\//'|sed -f - my.profile
#! /bin/sh
# my.profile
host1=www.sina.com.cn
host3=www.baidu.com
host4=www.taobao.com
test_ping() { echo "$(ping -c 3 $1 |grep avg|cut -d "/" -f4|cut -d "." -f1)" ; }
for host in $host1 $host3 $host4; do echo "$host: $(test_ping $host)"; done

RE_HASH

$>  grep host my.def|sed  's/\(host.\)=\(.\+\)/s\/\1=.\\+\/\1=\2\//'|sed -f - my.profile

RE_HASH

回复 7# sunzhiguolu


这坛子似乎对淘宝摆渡之类的域名过敏。

   

sunzhiguolu

回复 17# RE_HASH
您老人家也太牛了, 竟然可以回复 7 楼的我!!!

   

jcdiy0601

1. awk 'BEGIN{FS="="}NR==FNR{a[$1]=$2;next}NR>FNR{if(a[$1])print $1""FS""a[$1];else print}' 1 2

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moperyblue

回复 10# zy86416779


1.
想找第一次匹配的行  如果"="不在第一行的话 0,/=/和1,/=/效果一样,否则用0,/=/这种方式

2.
`h'
     Replace the contents of the hold space with the contents of the
     pattern space.

`H'
     Append a newline to the contents of the hold space, and then
     append the contents of the pattern space to that of the hold space.

zy86416779

回复 20# moperyblue
hi，我是知道h和H的含义的。我就是想知道//这个匹配的是什么呢。我做了个实验，我猜是只截取最后一行。还望能够得到比较权威的答复。

1. [root@study awksed]# cat file
   
2. 1
   
3. 2
   
4. 3
   
5. 4
   
6. 5
   
7. [root@study awksed]# sed -n '0,/5/{//p}' file
   
8. 5
   
9. [root@study awksed]# sed -n '0,/1/{//p}' file
   
10. 1
    
11. [root@study awksed]# sed -n '0,/2/{//p}' file
    
12. 2
    
13. [root@study awksed]# sed -n '0,/2/p' file   
    
14. 1
    
15. 2
    
16. [root@study awksed]#

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moperyblue

info sed =>


`/REGEXP/'
     This will select any line which matches the regular expression
     REGEXP.  If REGEXP itself includes any `/' characters, each must
     be escaped by a backslash (`\').

     The empty regular expression `//' repeats the last regular
     expression match (the same holds if the empty regular expression is
     passed to the `s' command).  Note that modifiers to regular
     expressions are evaluated when the regular expression is compiled,
     thus it is invalid to specify them together with the empty regular
     expression.


sed -n 0,/5/{//p} => sed -n 0,/5/{/5/p}

// 就是上一次正则表达式的内容