Truncate file at front

Question

A problem I was working on recently got me to wishing that I could lop off the front of a file. Kind of like a “truncate at front,” if you will. Truncating a file at the bac

Answer 1

may can achieve this goal in two steps

long fileLength; //file total length
long reserveLength; //reserve length until the file ending
int fd; //file open for read & write

sendfile(fd, fd, fileLength-reserveLength, reserveLength);
ftruncate(fd, reserveLength);