Samba has a special relationship to CUPS. Samba can be compiled with CUPS library support. Most recent installations have this support enabled. By default, CUPS linking is compiled into smbd and other Samba binaries. Of course, you can use CUPS even if Samba is not linked against libcups.so but there are some differences in required or supported configuration.

When Samba is compiled and linked with libcups, printcap = cups uses the CUPS API to list printers, submit jobs, query queues, and so on. Otherwise it maps to the System V commands with an additional -oraw option for printing. On a Linux system, you can use the ldd utility to find out if smbd has been linked with the libcups library ( ldd may not be present on other OS platforms, or its function may be embodied by a different command):

root# 

ldd `which smbd`

libssl.so.0.9.6 => /usr/lib/libssl.so.0.9.6 (0x4002d000)
libcrypto.so.0.9.6 => /usr/lib/libcrypto.so.0.9.6 (0x4005a000)
libcups.so.2 => /usr/lib/libcups.so.2 (0x40123000)
[....]

The line libcups.so.2 => /usr/lib/libcups.so.2 (0x40123000) shows there is CUPS support compiled into this version of Samba. If this is the case, and printing = cups is set, then any otherwise manually set print command in smb.conf is ignored . This is an important point to remember!