What is the oflag used to open a file in mode read + write?O_WRONLYO_RDONLYO_RDWR

1. Break Down the Problem

We need to identify the correct flag used to open a file in read and write mode among the given options:

• O_WRONLY
• O_RDONLY
• O_RDWR

2. Relevant Concepts

In file handling in programming (particularly in C or similar languages), file opening modes are defined by specific flags:

• O_WRONLY: Opens the file for write-only access.
• O_RDONLY: Opens the file for read-only access.
• O_RDWR: Opens the file for both reading and writing.

3. Analysis and Detail

By analyzing the descriptions above:

• O_WRONLY is not suitable because it indicates write-only access.
• O_RDONLY cannot be the answer, as it is strictly for read-only access.
• O_RDWR is the correct flag that allows both reading and writing to the file.

4. Verify and Summarize

The question specifically asks for the mode that allows both reading and writing. The flag O_RDWR is clearly defined for this purpose. Therefore, it is the most appropriate choice.

Final Answer

The correct oflag used to open a file in mode read + write is O_RDWR.