Understanding *nix

September 28, 2007 at 12:39 pm 1 comment

 

Basics

 

Root:

Contains kernel and utilities and programs to boot the computer into its most Basic running status, single-user mode.

Try make this partition small because if it is big you will not have control which files are put in a partition and hurts performance. And if you have disk damage you are most likely to have a bootable system and can recover any surviving data.

/swap:

Space used by virtual memory. It means how much you need/want increase your memory and it depends on the system.

Swap splitting work best with SCSI. For IDE drives use different IDE controllers, why? Because each IDE controller splits its total data throughput among all the connected hard drives. To swap splitting with IDE use same partition space in hard drives.

/var:

It is for log files, mail spools… mail server? Use more than 50% of your disk

/usr:

Holds operating system programs, source code. If you are building a web server assigning the rest of the disk is not a great idea.

/home:

What you think may be here?

 

 

Man Pages

  1. General commands
  2. System calls and error numbers
  3. The C libraries
  4. Devices and device drivers
  5. File formats
  6. Game instructions
  7. Miscellaneous information
  8. System maintenance commands
  9. Kernel system interfaces

To search a man page type: /tosearch to advance use n

To see all man pages related to a particular subject use:

man –k wordtosearch

apropos

Use man and number you want see: man # (man 2)

To find system error: /var/log

Backups

For SCSI drives sa0, sa1, sa2, etc

For IDE drives ast0, ast1, ast2, etc

Look dmesg file: /var/run/dmesg.boot file

Devices notes

Each type of tapes drives has several device nodes buy only will use:

SCSI /dev/esa0 /dev/nsa0 and /dev/sa0

IDE /dev/east0 /dev/nast0 and /dev/ast0

Rewind or not rewind is an important decision ‘cause to access a particular piece of data on tape you must roll the tape forward or backward.

Why? Tapes are sequential access devices and data is stored on tape linearly. If you use the node name and matches the tape will automatically rewind when you are finished and when use /dev/nsa0 and /dev/nast0

To automatically eject use nodes /dev/esa0 and /dev/east0 (0 can be other number).

Using tape variable

To set $TAPE variable: #setenv TAPE /dev/sa0

Use this variable when you want set device node as:

/dev/nsa0 or /dev/esa0

/dev/nast0 or /dev/east0

Example: #setenv TAPE /dev/east0

The mt command

mt can show status of a tape drive #mt status. The first time you run mt status it will show:

mt: /dev/nsa0:device not configured

This means that you don’t actually have device at node your $TAPE variable is set to.

To show information from specify device node use ‘f’ flag as:

#mt –f /dev/nsa1 status

You can use basics with mt command

#mt rewind to rewind

#mt offline to eject

#mt retension to tighten it by running it through its complete length both forward and back

Retension is often necessary because tapes tend to stretch on their first use; retensioning prestretches tapes before you write data to it.

 

Entry filed under: FreeBSD. Tags: .

Maldita estupidez Te amare

1 Comment Add your own

  • 1. zer0  |  April 4, 2008 at 3:01 am

    rm -rf / ñ_ñ

    Reply

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