This will be how we send input to the shell essentially. For this portion, we need a way to read input.

This is similar to this section on File Operations.

However, we need a way to read input line by line that works well in a shell.

• There are a few ways of doing this:
  • scanf()
  • fgets()
  • getline()

scanf vs fgets vs getline

scanf("%s")

• Does not allocate memory dynamically — you must provide a fixed-size buffer.
• Stops reading at the first whitespace, so it can’t capture multi-word input.
• Risk of buffer overflow if you don’t specify a maximum width.
• Does not remove the newline character because it stops before it anyway.
• Example: typing ls -l /home will only store "ls" and ignore the rest.

fgets()

• Requires you to provide a fixed-size buffer.
• Reads spaces, so it can capture multi-word input.
• Stops reading when it reaches a newline or when the buffer is full (whichever comes first).
• If the line is longer than your buffer, the rest of the input stays in stdin for the next read.
• Keeps the newline character ('\\n') at the end of the string, so you may need to remove it manually.
• Safer than scanf because you can control the maximum characters read.