How to use a shell variable inside sed when doing “d” command?

Question

In my bash, I wish to delete lines from 1 to ${number}, like this:

number=10
sed '1,${number}d' myfile

It failed with syntax error. I also tried "\\${number}", '"$number"', neithers works

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I changed to double quote, it works under command line, but not inside bash script file. How to make it work?

Answer 1

将sed表达式括在双引号内以插入变量number ：

sed "1,${number}d" file

Answer 2

Please use double quotes instead of single quotes while running sed this way. Read here for Difference between single and double quotes

Answer 3

I changed to double quote, it works under command line, but not inside bash script file

Assuming your bash script is:

sed "1,${number}d" myfile

you should export number variable in bash prompt so that it can be visible in bash script when it is run:

export number=10