To insert the value of the file_name variable into the command, you can use string interpolation. Here's an example:
file_name = "001.png"
system("i_view32.exe #{file_name} /fs")
In this code, the #{file_name} expression is used to insert the value of the file_name variable into the command string. When the system method is called, the resulting command will be:
i_view32.exe 001.png /fs
This should open the 001.png file in IrfanView in full-screen mode.