Look for the right source of information onlineHow to create, open, close, read and write filesWhat are file descriptorsWhat are the 3 standard file descriptors, what are their purpose and what are their POSIX namesHow to use the I/O system calls open, close, read and writeWhat are and how to use the flags O_RDONLY, O_WRONLY, O_RDWRWhat are file permissions, and how to set them when creating a file with the open system callWhat is a system callWhat is the difference between a function and a system call

Creating, opening, closing, reading, and writing files: In most programming languages, you can create a file using a built-in function. For example, in Python, you can use the open() function with the 'w' mode. To open a file, you can use the open() function with the 'r' mode. To close a file, you can use the close() method. To read a file, you can use the read() method. To write to a file, you can use the write() method.

File Descriptors: A file descriptor is a non-negative integer that is used to access a file or other input/output resource, such as a pipe or network socket. File descriptors form part of the POSIX application programming interface.

The 3 standard file descriptors are:

• Standard Input (stdin): This is the input stream where data is sent to the program. The POSIX name is 0.
• Standard Output (stdout): This is the output stream where a program writes its output data. The POSIX name is 1.
• Standard Error (stderr): This is another output stream typically used by programs to output error messages or diagnostics. The POSIX name is 2.

The I/O system calls open, close, read, and write are used to manipulate files in a low-level way. open is used to open a file, close to close it, read to read from it, and write to write to it.

The flags O_RDONLY, O_WRONLY, O_RDWR are used with the open system call to specify the mode in which the file should be opened. O_RDONLY opens the file for reading only, O_WRONLY for writing only, and O_RDWR for reading and writing.

File permissions determine who can read, write, or execute a file. When creating a file with the open system call, you can set the permissions using the mode argument.

A system call is a programmatic way in which a computer program requests a service from the kernel of the operating system it is executed on.

The difference between a function and a system call is that a function is a piece of code that is called by a program, while a system call is a programmatic way in which a computer program requests a service from the kernel of the operating system.