LINK Use the command to make a device that is associated with another
virtual ava1laDle to your configuration, based
upon information in that user's VM/370 directory entry. The format of
the LINK command is:
r
\ LINK [Tol userid vaddr1 (Asl vaddr2 [mode] [[PASS=] passwqrd 1 ]
\----
\ I1If your installation is using the password suppression facility, an I INVALID message is issued when a user attempts to enter the
\ for a DASD device on the LINK command line. The user must I wait for the EN1ER PASSWORD response before typing in the password. I This facility improves system security because the password I is automatically masked.
L [TOl userid
vaddr1
is the name of the user whose directory is to be
searched for device vaddr1. An asterisk (*) is used to specify
that the device is in your own VM/370 directory. If the keyword TO is omitted, the userid may not be "TO" or "T".
is the virtual device address (cuu) in the VM/370 directory
for that userid. [ASl vaddr2 mode
is the virtual address (cuu) that is to be assigned to the ievice for vour virtual machine. If the keyword AS is omitted, vaddr may not be "AS" or "A". If your virtual machine has the option, any address up to X'FPF' is valid; otherwise, any address up to X'5FP' is valid.
is the access mode; the primary access requested (read-only, write; or multiple) I and the alternate access (read-only or write) desired if the primary access is not available. Valid modes are: R access. The link is not done if any other user
has the disk in write status. R is the default mode if
the link is to another userid.
RR Read-onlv access. The link is established even if another
user has the disk in write status. w write access. The link is not done if any other user has the disk in read or write status. WR write and read access. If another user has the disk in
read or write status, an alternate access of read-only is
acceptable. M access. This means that a write-link is to be
given to the disk unless another user already has write
access to it, in which case no link is to be done.
section 5. Format of CP Commands 91

MF write-link. If another user already has write access to
the disk, a read-link is to be done. Note: Unpredictable results can occur when one user has a RIO-link to a device that is being updated by a user who
has the device in read/write status. MW Write-link. This link is established in all cases. More than one user writing to the same virtual device
can result in permanent loss of data.
If the mode is omitted, the default is R if the userid is
another user. If you are linking to one of your own disks,
the default is the "user access mode" as specified in the VM/370 directory for your disks. PASS= password is a one-to eight-character string that must match the access mode password for device vaddr1 in the VM/370 directory for
the user (userid) specified. The password should be specified only when the LINK is executed by a virtual machine (for
example, from CMS), since printing of the password is not
suppressed when included with the LINK command. The access
mode password cannot be the same as any of the access modes
(R, RR, W, WR, M, MR, or Mi) if the default mode is to be used. The access mode password should not be confused with a
user password.
1. If link to one of your own disks, no password is required.
Also, if the link is to a device whose password is ALL, meaning
that the device can be used by all users, the password is not
required. if the link is to any other userid, a password
for the desired device must be provided. If a LINK command is
issued from a CMS batch job, a password must be provided, even if
the device password is ALL.
2. When linking to a 2305 device, you gain access only to the virtual address specified and not to all eight addresses associated with
the device. 3. The access allowed by the LINK command to the vaddr1 device
belonqing to userid is summarized below. You read the columns down
to deteLmine the type of link that results. The first row
indicates the primary (and, optionally, the alternate) access mode
requested. The second row indicates whether read, write, or
multiple passwords exist in the VM/370 directory for the disk being
linked. The third row indicates whether the disk is already being
used, and if so, the mode of its access. The last row indicates
the type of link established. For example, the third column is inteLpLeted as follows: if you request a read access link (R) to a
disk that has a read password defined and that already is accessed
in read mode, you can establish a read link.
4. ViLtual Leserve/release processing cannot be requested by appending
a V to the mode operand of the LINK command line. Virtual reseLve/release processing can only be requested by means of the MDISK statement of the directory program. 92 IBM CP Command Reference for General Users