If multiple source files are indicated, the destination must be a directory, or an error will result.

The command is available in DEC RT-11,[3] OS/8,[4] RSX-11,[5] Intel ISIS-II,[6] iRMX 86,[7] DEC TOPS-10,[8] TOPS-20,[9] OpenVMS,[10] MetaComCo TRIPOS,[11] Heath Company HDOS,[12] Zilog Z80-RIO,[13] Microware OS-9,[14] DOS, DR FlexOS,[15] IBM/Toshiba 4690 OS,[16] TSL PC-MOS,[17] HP MPE/iX,[18] IBM OS/2,[19] Microsoft Windows,[20] Datalight ROM-DOS,[21] ReactOS,[22] SymbOS and DexOS.

The copy command is supported by Tim Paterson's SCP 86-DOS.

copy letter.txt con would output to stdout, like the type command.

There are two command-line switches to modify the behaviour when concatenating files: