［APUE2nd学习笔记］Ch3. File I/O

[trrrr]

unbuffered I/O

File descriptor: 0, 1, 2

open: returns the lowest-numbered unused FD
creat
close
lseek: could return negative number, file's offset can be larger than its current size(hole)
read
write

I/O efficiency: bufsize=4096

file descriptor: file descriptor flag, a pointer to a file table entry
file table entry: file status flags, current offset, a pointer to v-node table entry

pread, pwrite
dup, dup2
sync, fsync, fdatasync(delayed write)
fcntl
ioctl

/dev/fd/n, /dev/stdin, /dev/stdout, /dev/stderr