General queries...

SAMIR SHAH_1 — Thu, 22 Feb 2001 04:08:22 GMT

Hello friends,

I have general queries as follows.

1. What is the diff. between file system and logical volume?

2. What is the diff. between character device file and block device file.

3. How to read core dump file?

4. From my server startup scripts, how to pass the global variable to the .profile script of a particular user?

Thanks.

Samir.

Re: General queries...

Steven Sim Kok Leong — Thu, 22 Feb 2001 05:30:51 GMT

Hi,

Briefly...

1. What is the diff. between file system and logical volume?

A filesystem sits on top of a logical volume. In Windows terms, a logical volume on the LVM-unix level is analogous to partition you create in Windows. In windows, to create a filesystem, you perform a format on the partition. The equivalent at the Unix side is the newfs command to "format" the logical volume.

2. What is the diff. between character device file and block device file.

A character device reads and writes character streams while a block device reads and writes in blocks. Block devices (eg. hard disks) allow random access while character devices allow only sequential access (eg. tape devices)

3. How to read core dump file?

Some of the common methods:
a) file core (to identify what was the signal that cased the dump)
b) q4 tool (specifically for crash dumps)
c) other debuggers such as adb and gdb.

4. From my server startup scripts, how to pass the global variable to the .profile script of a particular user?

Your server startup scripts are only called when the system is started up, not when users are logged on to the system.

To allow a particular user to a particular variable setting when he or she is logged on, the variable must be set in the system /etc/profile or the user .profile or .login or .cshrc depending on the login shell set for the user.

To load system variables specified in /etc/rc.config.d/* configuration files, simply run the following in /etc/profile:
===========================================
cd /etc/rc.config.d
for file in *
do
. $file
done
===========================================

Hope this helps. Regards.

Steven Sim Kok Leong
Brainbench MVP for Unix Admin
http://www.brainbench.com

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General queries...

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