shell - how to use variable in sed '3d' ../log/file2.txt > ../log/file8.txt

Question

I want to delete third line of file named file2. Its running successfully.No Issues with it.

sed '3d' ../log/file2.txt > ../log/file8.txt

Now i want to use variable VAR1 (where VAR1=2).

I wrote the following command

sed "${VAR1+1}d" ../log/file2.txt > ../log/file8.txt

but this command deleting the 2nd line. No error while executing the command.But I am not getting expected output

Please help me How to use sed in this command to get the correct line to be deleted

Answer 1

尝试

sed "$((VAR1+1))d" ../log/file2.txt

Answer 2

使用变量和删除一行awk

var1=4
awk NR!=v v=$var1 ../log/file2.txt > ../log/file8.txt

这将删除4th行file2

为了使其更健壮，请使用 qutes

awk 'NR!=v' v="$var1" file