Truncating the first 100MB of a file in linux

Question

I am referring to How can you concatenate two huge files with very little spare disk space?

I\'m in the midst of implementing the following:

1. Allocate a

Answer 1

I found I had to use a combination of fallocate and sed before the file would shrink in size, so I had a 43MB file and I want to get it down to around 5MB

fallocate -p -o 0 -l 38m fallocate.log

I noticed this filled the first line with a bunch of "nonsense" characters but my file was still 43MB in size

I then used sed to delete the first line

sed -i 1d fallocate.log

and the file size is now 4.2MB in size.