RAMDISKADM(8) Maintenance Procedures RAMDISKADM(8)


ramdiskadm - administer ramdisk pseudo device


/usr/sbin/ramdiskadm -a name size [g | m | k | b]

/usr/sbin/ramdiskadm -d name



The ramdiskadm command administers ramdisk(4D), the ramdisk driver. Use
ramdiskadm to create a new named ramdisk device, delete an existing named
ramdisk, or list information about existing ramdisks.

Ramdisks created using ramdiskadm are not persistent across reboots.


The following options are supported:

-a name size
Create a ramdisk named name of size size and its
corresponding block and character device nodes.

name must be composed only of the characters a-z, A-Z,
0-9, _ (underbar), and - (hyphen), but it must not begin
with a hyphen. It must be no more than 32 characters
long. Ramdisk names must be unique.

The size can be a decimal number, or, when prefixed with
0x, a hexadecimal number, and can specify the size in
bytes (no suffix), 512-byte blocks (suffix b), kilobytes
(suffix k), megabytes (suffix m) or gigabytes (suffix g).
The size of the ramdisk actually created might be larger
than that specified, depending on the hardware

If the named ramdisk is successfully created, its block
device path is printed on standard out.

-d name
Delete an existing ramdisk of the name name. This command
succeeds only when the named ramdisk is not open. The
associated memory is freed and the device nodes are

You can delete only ramdisks created using ramdiskadm. It
is not possible to delete a ramdisk that was created
during the boot process.

Without options, ramdiskadm lists any existing ramdisks, their sizes (in
decimal), and whether they can be removed by ramdiskadm (see the
description of the -d option, above).


Example 1: Creating a 2MB Ramdisk Named mydisk

# ramdiskadm -a mydisk 2m

Example 2: Listing All Ramdisks

# ramdiskadm
Block Device Size Removable
/dev/ramdisk/miniroot 134217728 No
/dev/ramdisk/certfs 1048576 No
/dev/ramdisk/mydisk 2097152 Yes


ramdiskadm returns the following exit values:

Successful completion.

An error occurred.


See attributes(7) for descriptions of the following attributes:

|Interface Stability | Evolving |


ramdisk(4D), attributes(7)


The abilities of ramdiskadm and the privilege level of the person who
uses the utility are controlled by the permissions of /dev/ramdiskctl.
Read access allows query operations, for example, listing device
information. Write access is required to do any state-changing
operations, for example, creating or deleting ramdisks.

As shipped, /dev/ramdiskctl is owned by root, in group sys, and mode
0644, so all users can do query operations but only root can perform
state-changing operations. An administrator can give write access to non-
privileged users, allowing them to add or delete ramdisks. However,
granting such ability entails considerable risk; such privileges should
be given only to a trusted group.

March 25, 2003 RAMDISKADM(8)