sendfile · shipping

sendfile

sendfile is a Linux system call that transfers bytes between file descriptors within the kernel.

Success reports bytes transferred and can be shorter than requested. On zero-copy socket or pipe paths, source regions must remain unchanged until the receiver consumes them. Since Linux 5.12, a pipe output uses splice semantics. [1]

Closing the input descriptor does not mean queued data has been consumed. A file-to-pipe experiment demonstrates source mutation after return; it is not a TCP or durability test. [2]

Relations

related

splice, file-descriptor, atomic-rename, checksum

Citations

1. Linux man-pages 6.19: sendfile(2), return value and source lifetime (accessed 2026-10-17)
2. Hesela: Zero-copy transfers do not freeze source bytes (accessed 2026-10-18)

JSON: /data/terms/sendfile.json