User guide

Installing a DLT, SDLT, VS, LTO, or DAT Tape Drive Into a Linux Operating System
6464215-01, Rev B
January 2006
Accessing Devices Using /dev/st* Device Nodes 13
Interpreting the Device
Node File Listing
0
The following table explains each part of the displayed device node listing
shown in Reviewing the List of Device Files
on page 11.
Column Text Format Description
First
column
crw-rw---- These ten characters describe access type and permissions.
The first character indicates type of access device as follows:
•“
c” signifies that (n)st0* is a character (sequential access) device.
•“
b” signifies that (n)st0* is a block (random access) device.
The next nine characters indicate permissions for:
• the owner (characters 1 - 3)
• the group (characters 4 - 6)
• global users (characters 7 - 9)
Permissions are defined as follows:
• The first character of each set identifies read permissions. An “
r” indicates
read permission is granted; a
hyphen indicates read permission is denied.
• The second character of each set identifies write permissions. A “
w”
indicates write permission is granted; a
hyphen indicates write permission
is denied.
• The third character of each set identifies execute permissions. An “
x”
indicates execute permission is granted; a
hyphen indicates execute
permission is denied.
In the example shown, the device is sequential access. The owner and group
both have read/write permission but do not have execute permission; global
users have no permissions.
Second
column
1
Numeric character, not applicable.
Third
column
root
Identifies the owner of the device nodes.
This is always
root (root is the name of the superuser account).
Fourth
column
disk
Identifies the group associated with these device nodes.
This is always
disk.
Fifth
column
9, n
Identifies the major and minor numbers for that node.
Major Number: The first number is the major number. The major number
indexes a particular device driver in the kernel. To utilize the
st module, the
major number is always
9.
Minor Number: The second number is the minor number. The minor
number serves as a device driver parameter defining various characteristics
such as compression, block size, and density.
For a complete definition of all the major and minor numbers, see
device.txt at
/usr/src/linux-<kernel revision>/Documentation/device.txt.