End of Life Ruby 3.2 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →
class method
IO.new
IO.new(fd, mode = 'r', **opts) → io
io.c
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static VALUE
rb_io_initialize(int argc, VALUE *argv, VALUE io)
{
VALUE fnum, vmode;
rb_io_t *fp;
int fd, fmode, oflags = O_RDONLY;
convconfig_t convconfig;
VALUE opt;
#if defined(HAVE_FCNTL) && defined(F_GETFL)
int ofmode;
#else
struct stat st;
#endif
argc = rb_scan_args(argc, argv, "11:", &fnum, &vmode, &opt);
rb_io_extract_modeenc(&vmode, 0, opt, &oflags, &fmode, &convconfig);
fd = NUM2INT(fnum);
if (rb_reserved_fd_p(fd)) {
rb_raise(rb_eArgError, "The given fd is not accessible because RubyVM reserves it");
}
#if defined(HAVE_FCNTL) && defined(F_GETFL)
oflags = fcntl(fd, F_GETFL);
if (oflags == -1) rb_sys_fail(0);
#else
if (fstat(fd, &st) < 0) rb_sys_fail(0);
#endif
rb_update_max_fd(fd);
#if defined(HAVE_FCNTL) && defined(F_GETFL)
ofmode = rb_io_oflags_fmode(oflags);
if (NIL_P(vmode)) {
fmode = ofmode;
}
else if ((~ofmode & fmode) & FMODE_READWRITE) {
VALUE error = INT2FIX(EINVAL);
rb_exc_raise(rb_class_new_instance(1, &error, rb_eSystemCallError));
}
#endif
VALUE path = Qnil;
if (!NIL_P(opt)) {
if (rb_hash_aref(opt, sym_autoclose) == Qfalse) {
fmode |= FMODE_PREP;
}
path = rb_hash_aref(opt, RB_ID2SYM(idPath));
if (!NIL_P(path)) {
StringValue(path);
path = rb_str_new_frozen(path);
}
}
MakeOpenFile(io, fp);
fp->self = io;
fp->fd = fd;
fp->mode = fmode;
fp->encs = convconfig;
fp->pathv = path;
fp->timeout = Qnil;
clear_codeconv(fp);
io_check_tty(fp);
if (fileno(stdin) == fd)
fp->stdio_file = stdin;
else if (fileno(stdout) == fd)
fp->stdio_file = stdout;
else if (fileno(stderr) == fd)
fp->stdio_file = stderr;
if (fmode & FMODE_SETENC_BY_BOM) io_set_encoding_by_bom(io);
return io;
}
Creates and returns a new IO object (file stream) from a file descriptor.
IO.new may be useful for interaction with low-level libraries. For higher-level interactions, it may be simpler to create the file stream using File.open.
Argument fd must be a valid file descriptor (integer):
Example
path = 't.tmp' fd = IO.sysopen(path) # => 3 IO.new(fd) # => #<IO:fd 3>
The new IO object does not inherit encoding (because the integer file descriptor does not have an encoding):
Example
fd = IO.sysopen('t.rus', 'rb') io = IO.new(fd) io.external_encoding # => #<Encoding:UTF-8> # Not ASCII-8BIT.
Optional argument mode (defaults to ‘r’) must specify a valid mode; see Access Modes:
Example
IO.new(fd, 'w') # => #<IO:fd 3> IO.new(fd, File::WRONLY) # => #<IO:fd 3>
Optional keyword arguments opts specify:
Examples:
Example
IO.new(fd, internal_encoding: nil) # => #<IO:fd 3> IO.new(fd, autoclose: true) # => #<IO:fd 3>
Ruby version changes
-
3.2
-
Introduce
IO.new(..., path:)and promoteFile#pathtoIO#path. [Feature #19036]
-