The sys command is used to copy the system files from one drive to another, allowing the second drive to be bootable.
When running sys, the following files are command.com, io.sys, msdos.sys, and drvspace.bin are copied.
Sys is an external command that is available in the following Microsoft operating systems as sys.com.
Copies MS-DOS system files and command interpreter to a disk you specify.
SYS [drive1:][path] drive2:
|Specifies the location of the system files.
|Specifies the drive to where the files are copied.
Typing this command at the C: prompt with a formatted disk in the drive copies the system files to that disk and makes it bootable.
The sys.com file must be running on the drive containing the system files and the sys.com file. If you're running from the hard drive, this command is commonly located in the C:\Windows\COMMAND\ directory on Windows 95, 98, NT, and 2000 or in C:\DOS\ directory on Windows 3.x / DOS. This command can also run from a bootable diskette assuming that it contains all the necessary files.
If, when booting your computer, you get "Missing command interpreter," it indicates the command.com is missing. To resolve this issue, boot from a disk with sys.com and command.com, type sys c: from the A:\>, remove the disk and reboot the computer.