sed/bash 中的变量替换

Question

I'm trying to do variable substitution in sed/bash.

I have seen this example available here , but it does not replace the data as required. The value observed in line 20 of $C_CONF is $RAM , when I want it to be 100 .

Line 20 of $C_CONF is AllowedRAMSpace=SomeValue and I would like to change that value on-the-fly.

This is the trick I created, but it is a very ugly and inefficient one.

 32 for RAM in 100 #80 60 40 20
 33 do  
 34     sudo sed -i -re 's/(AllowedRAMSpace=)[^=]*$/\1"'"$RAM"'"/' $C_CONF
 35     sudo sed -i '20s/"//' $C_CONF
 36     sudo sed -i '20s/"//' $C_CONF 
 37 done

What is the other way?

Answer 1

尝试使用 awk 代替

awk 'BEGIN{RAM=100}NR==20{print gensub(/(AllowedRAMSpace=)([^=].*$)/,"\\1"RAM,"g", $0)}' filename