instance method
File#truncate
(::int length) -> 0
file.truncate(integer) → 0
file.c
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static VALUE
rb_file_truncate(VALUE obj, VALUE len)
{
rb_io_t *fptr;
struct ftruncate_arg fa;
fa.pos = NUM2OFFT(len);
GetOpenFile(obj, fptr);
if (!(fptr->mode & FMODE_WRITABLE)) {
rb_raise(rb_eIOError, "not opened for writing");
}
rb_io_flush_raw(obj, 0);
fa.fd = fptr->fd;
if ((int)rb_io_blocking_region(fptr, nogvl_ftruncate, &fa) < 0) {
rb_sys_fail_path(fptr->pathv);
}
return INT2FIX(0);
}
Truncates file to at most integer bytes. The file must be opened for writing. Not available on all platforms.
Example
f = File.new("out", "w") f.syswrite("1234567890") #=> 10 f.truncate(5) #=> 0 f.close() #=> nil File.size("out") #=> 5