First knowledge of mounting and assigning tasks in linux

Two Mount methods affect the script for mounting external devices:/etc/fstab boot script: inittab contains some running command user script: login. defs limits the user's password modification time and idgid expiration time .. Automatic mounting: attach an image disc to a VM --- VM -...

 

Two Mount methods

 

Script that affects mounting external devices:/etc/fstab

 

Boot script: the inittab contains some running commands.

 

User script: login. defs limits the user's password modification time and id gid expiration time ..

 

Automatic mounting

 

Attach an image disk

 

Virtual machine --- VM --- settings --- CD/DVD --- specify the path of the scene file (the first disc )---

 

Device status: the first Device status is recommended.

 

Connected: as long as an external device is mounted, the system will identify

 

Connectedpower on: identify once upon startup;

 

 

 

 

Open: Vi/etc/fstab

 

Syntax format:

 

Each row is a record.

 

6 fields

 

External device name	Mount point	File system type	Restrictions	Power-on self-check	Backup or not (priority)
/Dev/cdrom	/Mnt/	Ext3	Hardware device (default: ULTS)	0, 1	0, 1

Mount your external device by writing a new line of data in this format.

 

Command mount:

 

# Mount-t type external device mount point

 

Note: Mount point settings

 

It is not recommended to map directly to/mnt

 

Prevent/mnt from being mounted to other devices (one by one directory (create a directory under/mnt ))

 

Try to create a new directory for mounting

 

 

Detach a USB flash drive from an external device

 

Umount mobile device or mount point

 

Umount/dev/spd (/mnt/)

 

 

 

 

 

Schedule tasks

1. schedule tasks (repetitive) cron

 

1) Note: One-time task at (which can be viewed on the fifth day of week 16th)

 

Cron is a task scheduling tool installed in the same rpm package.

 

Check whether the software has been installed

 

# Rpm-qa | grepcron

 

2) enable the corresponding service

 

The system checks the corresponding script file every minute.

 

# Service crond start

 

# Vi/etc/crontab

 

Vi open the directory as follows:

 

[Root @ localhost cdrom] # cat/etc/crontab

 

SHELL =/bin/bash

 

PATH =/sbin:/bin:/usr/sbin:/usr/bin

 

MAILTO = root

 

HOME =/

 

Name = value definition variable

 

# Run-parts

 

01 *** root run-parts/etc/cron. hourly

 

02 4 *** root run-parts/etc/cron. daily

 

22 4 ** 0 root run-parts/etc/cron. weekly

 

42 4 1 ** root run-parts/etc/cron. monthly

 

 

 

42 4 1 ** rootrun-parts/etc/cron. hourly

 

Minute Hour date month week user script

 

0-59 0-23 1-31 1-12 0-6

 

The first way to schedule tasks: compile files in a fixed Directory

 

Replace "*" with the meaning of "every day" (every month .....)

 

 

 

For example, schedule the system to replicate every hour.

 

# Cd/etc/cron. hourly

 

# Touch filename

 

# Vi filename

 

Write the command you want to execute

 

42 4 1 ** command

 

 

 

Method 2: directly use crontab to edit the script

 

# Crontab-e the following task format is saved to/var/spool/cron by default.

 

-E edit

 

-L list

 

-R remove

 

-U zhy specifies a user to execute the task. by default, root is not written.

 

Root schedule task crontab-e

 

Root specifies the lisi execution task crontab-u lisi-e

 

 

 

Schedule tasks:

 

Back up/etc to external devices at half past four P.M., January 1, December 25 every year

 

30 16 25 12 * cp-r/etc/mnt/cdrom

 

Back up/etc to external devices from four o'clock P.M. to half past six on January 1, December 25

 

30 4-6 25 12 * cp-r/etc/mnt/cdrom

 

Note:

 

Separate time points with spaces or tabs

 

The value range is 16-18.

 

Independent time (16, 18)

 

* Indicates any time point

 

 

 

Based on the above two ways of adding tasks, they have the same syntax for adding tasks.

 

Back up/etc to external devices from four o'clock P.M. to half past six on January 1, December 25

 

30 4-6 25 12 * cp-r/etc/mnt/cdrom

 

However, for the first type, the data is usually used less, and the second type has more data.

 

 

 

 

 

 

 

Add hard disk --

 

Step 1:

 

Steps for adding a hard disk

 

Disable the system: otherwise, only SCSI hard disks can be installed.

 

In the VM --- settings ---- HARD --- add --- next-IDE

 

Restart a VM

 

Open Terminal

 

# Fdisk-l

 

External hardware devices recognized by the detection system

 

There are two hard disk connection methods

 

 

 

IDE type

 

Hard disk

 

/Etc/hda indicates the first hard disk

 

/Etc/hda0 --- the first primary partition on the first hard disk

 

/Etc/hda0 --- the first primary partition on the first hard disk

 

 

 

/Etc/hdb indicates the second hard disk

 

/Etc/hdb0 --- the first primary partition on the second hard disk

 

/Etc/hdb0 --- the first primary partition on the second hard disk

 

 

USB flash drive sda sdb

 

 

 

 

 

 

 

Scsi type

 

Hard disk

 

/Etc/sda indicates the first hard disk

 

/Etc/sda0 --- the first primary partition on the first hard disk

 

/Etc/sda0 --- the first primary partition on the first hard disk

 

 

 

/Etc/sdb indicates the second hard disk

 

/Etc/sdb0 --- the first primary partition on the second hard disk

 

/Etc/sdb0 --- the first primary partition on the second hard disk

 

USB flash drive: sda sdb

 

From the column wjc19911118