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This function opens a file,
in the mode specified in the string mode.
It returns a new file handle,
or, in case of errors, nil plus an error message.
The mode string can be any of the following:
- "r": read mode (the default);
- "w": write mode;
- "a": append mode;
- "r+": update mode, all previous data is preserved;
- "w+": update mode, all previous data is erased;
- "a+": append update mode, previous data is preserved,
writing is only allowed at the end of file.
The mode string can also have a 'b' at the end,
which is needed in some systems to open the file in binary mode.
This string is exactly what is used in the
standard C function fopen. |