Linux-cento OS Learning Note 3

1. View System Information

The uname directive can be used to see what system is currently

Uname-r to view kernel version

To view the CPU information is to use the Cat/proc/cpuinfo

Viewing memory information using Cat/proc/meminfo

Date View system date

Cal 2018 Displays the 2018 calendar table

Setting the system time requires the use of date-s under the root user

2. Disk operation

DF-LH Show Current disk status

Du-sh/home/xxx/home/xxx is the directory name

To view the current directory as a disk size

Repair Disk fsck/dev/xxx The command will repair the disk automatically

/dev/xxx is the directory name

Mount View Mount disk information

MOUNT/DEV/XXX mount the specified disk

UMOUNT/DEV/XXX uninstalling the specified disk

3. Memory operation

See Overall memory usage free-m

View the usage top of each process memory

4. Network operation

Ping test connectivity, too common

5.linux Software Installation Method

The first way

RPM command

1. Check if a software is installed

#rpm-qa|grep Java

2. Uninstalling the Installed software

#rpm-e--nodeps xxxxxxx

3. Installing the Software

#rpm-IVH xxx.rpm

The second way

Tar source compilation is not recommended for use

Insert a digression, for the use of zip software

Unzip $ unzip Xxx.zip

Compress $ zip yy.zip file

and the Tar Software

Extract

Extract to current directory $ TAR-ZXVF xxxx.tar.gz

Unzip to the specified directory $ tar-zxvf xxxx.tar.gz-c dir

Compression

$ tar-zcvf xxxx.tar.gz dir

Third Kind

Yum

Very common, but need to configure the source

6. How to set sudo permissions for normal users

Switch to root user first

Then #vi/etc/sudoers

Add the following code in the first line

XX all= (Root) nopasswd:all

XX is replaced with the current user name can be

7. Firewalls

View firewall status
$ sudo service iptables status

Shutting down the firewall
$ sudo service iptables stop

Start the firewall
$ sudo service iptables start

Permanently set firewall off
$ sudo chkconfig iptables off

8.SELINUX

Turn off the service as soon as you change selinux=enforcing in/etc/sysconfig/selinux to selinux=disabled

9.crontab

For users

Each user can schedule their own tasks

Create a scheduled task under a user

For example, implementation occurs every minute, and time is written to the specified file

$ crontab -e### first crobtab*/1 * * * * /bin/date >> /home/freezeriver/bf-log.txt

List all the current scheduled tasks
Crontab-l

Delete all Scheduled Tasks
Crontab-r

Linux-cento OS Learning Note 3