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Caution
The
printing parameter is normally a service-level parameter. Since it is included
here in the
[global]
section, it will take effect for all printer shares that are not
defined differently. Samba-3 no longer supports the SOFTQ printing system.
load printers = yes
Tells Samba to create automatically all available printer shares. Available printer shares are discovered by
scanning the printcap file. All created printer shares are also loaded for browsing. If you use this
parameter, you do not need to specify separate shares for each printer. Each automatically created printer
share will clone the configuration options found in the
[printers]
section. (The
load printers = no
setting will allow you to specify each UNIX printer you want to
share separately, leaving out some you do not want to be publicly visible and available).
show add printer wizard = yes
Setting is normally enabled by default (even if the parameter is not specified in smb.conf). It causes the
Add Printer Wizard icon to appear in the Printers folder of the Samba
host's share listing (as shown in Network Neighborhood or by the
net
view
command). To disable it, you need to explicitly set it to no (commenting
it out will not suffice). The
Add Printer Wizard
lets you upload a printer driver to
the
[print$]
share and associate it with a printer (if the respective queue exists
before the action), or exchange a printer's driver for any other previously uploaded driver.
max print jobs = 100
Sets the upper limit to 100 print jobs being active on the Samba server at any one time. Should a client
submit a job that exceeds this number, a "no more space available on server" type of error message will be
returned by Samba to the client. A setting of zero (the default) means there is
no
limit
at all.
printcap name = /etc/printcap
Tells Samba where to look for a list of available printer names. Where CUPS is used, make sure that a printcap
file is written. This is controlled by the Printcap directive in the
cupsd.conf file.
printer admin = @ntadmin
Members of the ntadmin group should be able to add drivers and set printer properties
(ntadmin is only an example name; it needs to be a valid UNIX group name); root is
implicitly always a
printer admin. The @ sign precedes group names
in the /etc/group. A printer admin can do anything to printers via the remote
administration interfaces offered by MS-RPC (see
Printing Developments Since
Samba-2.2). In larger installations, the
printer admin parameter is normally a
per-share parameter. This permits different groups to administer each printer share.
lpq cache time = 20
Controls the cache time for the results of the lpq command. It prevents the lpq command being called too often
and reduces the load on a heavily used print server.
use client driver = no
If set to yes, only takes effect for Windows NT/200x/XP clients (and not for Win
95/98/ME). Its default value is No (or False). It must
not
be enabled on print shares (with a yes or
true setting) that have valid drivers installed on the Samba server. For more detailed
explanations, see the smb.conf man page.
The printers section is the second special section. If a section with this name appears in the smb.conf,
users are able to connect to any printer specified in the Samba host's printcap file, because Samba on startup
then creates a printer share for every printer name it finds in the printcap file. You could regard this
section as a convenient shortcut to share all printers with minimal configuration. It is also a container for
settings that should apply as default to all printers. (For more details, see the smb.conf man page.)
Settings inside this container must be share-level parameters.
-
comment = All printers
-
The
comment is shown next to the share if
a client queries the server, either via Network Neighborhood or with
the
net view
command, to list available shares.
-
printable = yes
-
The
[printers]
service
must
be declared as printable. If you specify otherwise, smbd will refuse to load at
startup. This parameter allows connected clients to open, write to, and submit spool files
into the directory specified with the
path
parameter for this service. It is used by Samba to differentiate printer shares from
file shares.
-
path = /var/spool/samba
-
Must point to a directory used by Samba to spool incoming print files.
It
must not be the same as the spool directory specified in the configuration of your UNIX
print subsystem!
The path typically points to a directory that is world
writable, with the
sticky
bit set to it.
-
browseable = no
-
Is always set to no if
printable = yes. It makes
the
[printer]
share itself invisible in the list of
available shares in a
net view
command or in the Explorer browse
list. (You will of course see the individual printers.)
-
guest ok = yes
-
If this parameter is set to yes, no password is required to
connect to the printer's service. Access will be granted with the privileges of the
guest account. On many systems the guest
account will map to a user named "nobody." This user will usually be found
in the UNIX passwd file with an empty password, but with no valid UNIX login. On some
systems the guest account might not have the privilege to be able to print. Test this
by logging in as your guest user using
su - guest
and run a system
print command like:
lpr -P printername /etc/motd
-
public = yes
-
Is a synonym for
guest ok = yes.
Since we have
guest ok = yes, it
really does not need to be here. (This leads to the interesting question, “What if I
by accident have two contradictory settings for the same share?” The answer is that the
last one encountered by Samba wins.
testparm
does not complain about different settings
of the same parameter for the same share. You can test this by setting up multiple
lines for the
guest account
parameter with different usernames,
and then run testparm to see which one is actually used by Samba.)
-
read only = yes
-
Normally (for other types of shares) prevents users from creating or modifying files
in the service's directory. However, in a
printable
service, it is
always
allowed to write to the directory (if user privileges allow the
connection), but only via print spooling operations. Normal write operations are not permitted.
-
writable = no
-
Is a synonym for
read only = yes.
Any [my_printer_name] Section
If a
[my_printer_name]
section appears in the smb.conf file, which includes the
parameter
printable = yes Samba will configure it as a printer share.
Windows 9x/Me clients may have problems with connecting or loading printer drivers if the share name has more
than eight characters. Do not name a printer share with a name that may conflict with an existing user or file
share name. On client connection requests, Samba always tries to find file shares with that name first. If it
finds one, it will connect to this and will not connect to a printer with the same name!
-
comment = Printer with Restricted Access
-
The comment says it all.
-
path = /var/spool/samba_my_printer
-
Sets the spooling area for this printer to a directory other than the default. It is not
necessary to set it differently, but the option is available.
-
printer admin = kurt
-
The printer admin definition is different for this explicitly defined printer share from the general
[printers]
share. It is not a requirement; we did it to show that it is possible.
-
browseable = yes
-
This makes the printer browseable so the clients may conveniently find it when browsing the
Network Neighborhood.
-
printable = yes
-
See
Section 20.4.1.2.
-
writable = no
-
See
Section 20.4.1.2.
-
hosts allow = 10.160.50.,10.160.51.
-
Here we exercise a certain degree of access control by using the
hosts allow
and
hosts deny parameters. This is not by any means a safe bet. It is not a
way to secure your printers. This line accepts all clients from a certain subnet in a first evaluation of
access control.
-
hosts deny = turbo_xp,10.160.50.23,10.160.51.60
-
All listed hosts are not allowed here (even if they belong to the allowed subnets). As
you can see, you could name IP addresses as well as NetBIOS hostnames here.
-
guest ok = no
-
This printer is not open for the guest account.
In each section defining a printer (or in the
[printers]
section),
a
print command
parameter may be defined. It sets a command to process the files
that have been placed into the Samba print spool directory for that printer. (That spool directory was,
if you remember, set up with the
path parameter). Typically,
this command will submit the spool file to the Samba host's print subsystem, using the suitable system
print command. But there is no requirement that this needs to be the case. For debugging or
some other reason, you may want to do something completely different than print the file. An example is a
command that just copies the print file to a temporary location for further investigation when you need
to debug printing. If you craft your own print commands (or even develop print command shell scripts),
make sure you pay attention to the need to remove the files from the Samba spool directory. Otherwise,
your hard disk may soon suffer from shortage of free space.
Default UNIX System Printing Commands
You learned earlier that Samba, in most cases, uses its built-in settings for many parameters if it cannot
find an explicitly stated one in its configuration file. The same is true for the
print command. The default print command varies depending on the
printing parameter
setting. In the commands listed in
Default Printing Settings , you will
notice some parameters of the form
%X
where
X
is
p, s,
J
, and so on. These letters stand for printer name, spool file, and job ID, respectively. They are
explained in more detail in
Default Printing Settings presents an overview
of key printing options but excludes the special case of CUPS, is discussed in
CUPS Printing Support.
Table20.1.Default Printing Settings
| Setting |
Default Printing Commands |
|
printing = bsd|aix|lprng|plp |
print command is
lpr -r -P%p %s
|
|
printing = sysv|hpux |
print command is
lp -c -P%p %s; rm %s
|
|
printing = qnx |
print command is
lp -r -P%p -s %s
|
|
printing = bsd|aix|lprng|plp |
lpq command is
lpq -P%p
|
|
printing = sysv|hpux |
lpq command is
lpstat -o%p
|
|
printing = qnx |
lpq command is
lpq -P%p
|
|
printing = bsd|aix|lprng|plp |
lprm command is
lprm -P%p %j
|
|
printing = sysv|hpux |
lprm command is
cancel %p-%j
|
|
printing = qnx |
lprm command is
cancel %p-%j
|
|
printing = bsd|aix|lprng|plp |
lppause command is
lp -i %p-%j -H hold
|
|
printing = sysv|hpux |
lppause command (...is empty) |
|
printing = qnx |
lppause command (...is empty) |
|
printing = bsd|aix|lprng|plp |
lpresume command is
lp -i %p-%j -H resume
|
|
printing = sysv|hpux |
lpresume command (...is empty) |
|
printing = qnx |
lpresume command (...is empty) |
For
printing = CUPS
, if Samba is compiled against libcups, it uses the CUPS API to
submit jobs. (It is a good idea also to set
printcap = cups in case your
cupsd.conf is set to write its autogenerated printcap file to an unusual place).
Otherwise, Samba maps to the System V printing commands with the -oraw option for printing; that is, it uses
lp -c -d%p -oraw; rm %s
. With
printing = cups
, and if Samba is
compiled against libcups, any manually set print command will be ignored!
After a print job has finished spooling to a service, the
print command will be used
by Samba via a system() call to process the spool file. Usually the command specified will submit the spool
file to the host's printing subsystem. But there is no requirement at all that this must be the case. The
print subsystem may not remove the spool file on its own, so whatever command you specify, you should ensure
that the spool file is deleted after it has been processed.
There is no difficulty with using your own customized print commands with the traditional printing systems.
However, if you do not wish to roll your own, you should be well informed about the default built-in commands
that Samba uses for each printing subsystem (see
Default Printing
Settings). In all the commands listed in the last paragraphs, you see parameters of the form
%X
. These are
macros
, or shortcuts, used as placeholders for the
names of real objects. At the time of running a command with such a placeholder, Samba will insert the
appropriate value automatically. Print commands can handle all Samba macro substitutions. In regard to
printing, the following ones do have special relevance:
-
%s, %f
the path to the spool file name.
-
%p
the appropriate printer name.
-
%J
the job name as transmitted by the client.
-
%c
the number of printed pages of the spooled job (if known).
-
%z
the size of the spooled print job (in bytes).
The print command must contain at least one occurrence of
%s
or
%f
. The
%p
is optional. If no printer name is supplied,
the
%p
will be silently removed from the print command. In this case, the job is
sent to the default printer.
If specified in the
[global]
section, the print command given will be
used for any printable service that does not have its own print command specified. If there is neither a
specified print command for a printable service nor a global print command, spool files will be created
but not processed! Most importantly, print files will not be removed, so they will consume disk space.
Printing may fail on some UNIX systems when using the
nobody
account. If this happens, create an
alternative guest account and give it the privilege to print. Set up this guest account in the
[global]
section with the
guest account
parameter.
You can form quite complex print commands. You need to realize that print commands are just
passed to a UNIX shell. The shell is able to expand the included environment variables as
usual. (The syntax to include a UNIX environment variable
$variable
in the Samba print command is
%$variable
.) To give you a working
print command example, the following will log a print job
to /tmp/print.log, print the file, then remove it. The semicolon (“;”
is the usual separator for commands in shell scripts:
print command = echo Printing %s >> /tmp/print.log; lpr -P %p %s; rm %s
|
You may have to vary your own command considerably from this example depending on how you normally print
files on your system. The default for the
print command
parameter varies depending on the setting of the
printing
parameter. Another example is:
print command = /usr/local/samba/bin/myprintscript %p %s
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