conio.h is a C header file used in DOS applications for console input and output.

Its member functions are:

kbhit - Determines if a keyboard key was pressed.
getch - Reads a character directly from the console without buffer, and without echo.
getche - Reads a character directly from the console without buffer, but with echo.
ungetch - Puts the character c back into the keyboard buffers.
cgets - Reads a string directly from the console.
cscanf - Reads formatted values directly from the console.
putch - Writes a character directly to the console.
cputs - Writes a string directly to the console.
cprintf - Formats values and writes them directly to the console.
clrscr - Clears the screen.

There is a linux implementation available for download at:

sourceforge.net/projects/linux-conioh/

It needs ncurses to be installed for it to work:

sudo apt-get install libncurses5-dev

When compiling my code I included the lncurses linker option.
Even though the compiler knows what the function calls look like by including the header, the linker needs the library file to find the relevant code

This can be done like this:
g++ -o binary_output file1.cpp file1.h main.cpp -lncurses