cat Command
===========

The `cat` command allows you to display the contents of a file in the terminal or redirect the contents into another file. It can also display file contents in hexadecimal format and support file creation under certain conditions.

Usage
-----
The basic syntax for the `cat` command is as follows:

.. code-block::

    cat <input_file> [--hex] [>> <output_file>] [-f]

Arguments
----------

- `input_file`: (Required) The path of the input file whose contents you want to display.
- `--hex`: (Optional) This option causes the output to be displayed in hexadecimal format.
- `>> output_file`: (Optional) Redirects the output to a specified file, appending to it. If the output file does not exist, an error will occur unless the `-f` option is used.
- `-f`: (Optional) Forces the creation of a new file if the output file does not exist.

Description
-----------
The `cat` command is used to read the contents of an input file and display them in the terminal. If the `--hex` option is specified, the contents are displayed in hexadecimal format, with each byte represented by two hexadecimal digits.

If the `>> output_file` argument is provided, the contents of the input file are written to the specified output file. If the output file does not exist, the command will fail unless the `-f` option is used to force the creation of a new file.

Options
-------

- **--hex**: This option causes the contents of the input file to be displayed in hexadecimal format, with one byte per space.
  
- **>> output_file**: Redirects the output to the specified file. The file will be appended to if it exists.

- **-f**: Forces the creation of the output file if it does not exist. Use this option when the output file must be created, even if it is missing.

Examples
--------

1. **Display the contents of a file:**

   .. code-block::

       cat /path/to/input.txt

   This will print the contents of `input.txt` to the terminal.

2. **Display the contents of a file in hexadecimal format:**

   .. code-block::

       cat /path/to/input.txt --hex

   This will display the file contents as hexadecimal values.

3. **Redirect the contents of a file to another file:**

   .. code-block::

       cat /path/to/input.txt >> /path/to/output.txt

   This will append the contents of `input.txt` to `output.txt`.

4. **Force the creation of an output file if it does not exist:**

   .. code-block::

       cat /path/to/input.txt >> /path/to/output.txt -f

   This will create `output.txt` if it doesn't exist and append the contents of `input.txt` to it.

Error Handling
--------------
If there is an error with any of the specified parameters, the following messages will be shown:

- **"Invalid input file path"**: This occurs if the input file path provided cannot be found or is incorrect.
- **"Invalid output file path"**: This occurs if the specified output file path is invalid or cannot be opened for writing.
- **"No file selected to cat"**: This occurs if no input file is specified when running the command.
- **"Error opening source file"**: This indicates that the source file could not be opened for reading.
- **"Error while reading data from source file"**: This indicates a failure during the file reading operation.
- **"Error while writing data into destination stream"**: This indicates an issue when writing data into the output stream (target file).
- **"Error while copying the file content"**: This indicates a failure in copying data from the source file to the destination.

Notes
-----
- If you use the `>> output_file` option without specifying an output file path, the command will fail.
- The `cat` command reads the entire file into memory in buffered chunks. If the file is large, make sure that enough memory is available.
- The `-f` flag can be used to force file creation if an output file does not exist.