| "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. Suppresses EOL <-> CRLF conversion on Windows. And sets external encoding to ASCII-8BIT unless explicitly specified. (This flag may only appear in conjunction with the above flags. For example, File.new("test.txt", "rb") would open test.txt in read-only mode as a binary file.) |
| "t" | Text file mode. (This flag may only appear in conjunction with the above flags. For example, File.new("test.txt", "wt") would open test.txt in write-only mode as a text file.) |
