What are the Ruby File.open modes and options?

In Ruby IO module documentation, I suppose.

Mode |  Meaning-----+--------------------------------------------------------"r"  |  Read-only, starts at beginning of file  (default mode).-----+--------------------------------------------------------"r+" |  Read-write, starts at beginning of file.-----+--------------------------------------------------------"w"  |  Write-only, truncates existing file     |  to zero length or creates a new file for writing.-----+--------------------------------------------------------"w+" |  Read-write, truncates existing file to zero length     |  or creates a new file for reading and writing.-----+--------------------------------------------------------"a"  |  Write-only, starts at end of file if file exists,     |  otherwise creates a new file for writing.-----+--------------------------------------------------------"a+" |  Read-write, starts at end of file if file exists,     |  otherwise creates a new file for reading and     |  writing.-----+--------------------------------------------------------"b"  |  Binary file mode (may appear with     |  any of the key letters listed above).     |  Suppresses EOL <-> CRLF conversion on Windows. And     |  sets external encoding to ASCII-8BIT unless explicitly     |  specified.-----+--------------------------------------------------------"t"  |  Text file mode (may appear with     |  any of the key letters listed above except "b").

opt is new for ruby 1.9. The various options are documented in IO.new : www.ruby-doc.org/core/IO.html