IO#fsync

() -> ::Integer?

fsync → 0

static VALUE
rb_io_fsync(VALUE io)
{
    rb_io_t *fptr;

    io = GetWriteIO(io);
    GetOpenFile(io, fptr);

    if (io_fflush(fptr) < 0)
        rb_sys_fail_on_write(fptr);

    if ((int)rb_io_blocking_region(fptr, nogvl_fsync, fptr))
        rb_sys_fail_path(fptr->pathv);

    return INT2FIX(0);
}

Immediately writes to disk all data buffered in the stream, via the operating system’s fsync(2).

Note this difference:

IO#sync=: Ensures that data is flushed from the stream’s internal buffers, but does not guarantee that the operating system actually writes the data to disk.
IO#fsync: Ensures both that data is flushed from internal buffers, and that data is written to disk.

Raises an exception if the operating system does not support fsync(2).

See also #flush #getbyte #fileno #getc also in 4.1 · 4.0 · 3.3 · 3.2 · 3.1 · 3.0

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