How to delete lines from a variable line number to the last line?

Question

In bash, I defined a variable n, from which value of line number to the last line is what I am going to delete.

I tried

sed -i '${n},$d' file

but the error msg is:

sed: -e expression #1, char 5: extra characters after command

Any thoughts about how to correct the use of sed? I suspect it is because of two $ in the sed, one is for variable, the other is for the last line number.

sed -i "${n},$d" test sed: -e expression #1, char 2: unexpected `,' — Lei Zhang, Feb 27 '16 at 00:34
@LeiZhang because [shell expansion](http://www.tldp.org/LDP/Bash-Beginners-Guide/html/sect_03_04.html) doesn't happen inside single quotes `'`. — Joao Morais, Feb 27 '16 at 01:14

score 1 · Answer 1 · answered Feb 27 '16 at 02:23

1

For portability, clarity, and safety, the following would be reasonable:

sed -i.bak -e "${n},\$d" file

answered Feb 27 '16 at 02:23

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How to delete lines from a variable line number to the last line?

1 Answers1