Shulou(Shulou.com)06/01 Report--

What is the use of server management in Linux? in view of this problem, this article introduces the corresponding analysis and solutions in detail, hoping to help more partners who want to solve this problem to find a more simple and easy way.

1. Install webmin

The code is as follows:

# install webmin

Cd / usr/local/ieternal/

Mkdir download

Cd download

Wget http://downloads.sourceforge.net/project/webadmin/webmin/1.660/webmin-1.660-1.noarch.rpm?r=http%3A%2F%2Fwww.webmin.cn%2F&ts=1387801624&use_mirror=jaist

Rpm-U webmin-1.660-1.noarch.rpm

At this point, you can access it through: http://115.28.9.136:10000/. The user name and password are root.

2. SSH Tunnel port forwarding, port proxy

The code is as follows:

#

# SSH Tunnel; has been tested and got through

#

# Public network server public network IP: 115.28.9.136

# Private network IP of public network server: 10.144.7.195

# Private network server private network IP: 10.144.7.191

# 1 sign in to 115.28.9.136 first

Ssh root@115.28.9.136-p 22

# modify ssh configuration through webmin and apply changes

# essentially / etc/ssh/sshd_config file

GatewayPorts yes

# 2 Log in to 10.144.7.191 on 136

Ssh root@10.144.7.191-p 22

# 3 execute on 10.144.7.191:

# that is, through this SSH, log in to the 195 machine in the background and listen to the port 19122.

# at this time, the request for access to 136Drex19122 is forwarded to the local port 22.

#-Nf means background command

Ssh-Nf 10.144.7.195-R 19122 10.144.7.191

# at this point, the client logs in through 115.28.9.136VR 19122, and actually logs in to 10.144.7.191V22 server.

3. Install squid Agent

The code is as follows:

# 1. Install squid

Yum-y remove squid

Yum-y install squid

# 2. Modify the configuration file

# search "http_access deny all" instead of "http_access allow all"

# ESC, / http_access can search

Vim / etc/squid/squid.conf

# perform the following modifications

# http_access deny CONNECT! SSL_ports

Http_access allow CONNECT! SSL_ports

# http_access deny all

Http_access allow all

# coredump_dir / var/spool/squid

Coredump_dir / usr/local/ieternal/squid_cache

# 3. Set cache directory

#! The users and user groups of the directory must be modified

Mkdir / usr/local/ieternal/squid_cache

Chown squid:squid / usr/local/ieternal/squid_cache

Cd / usr/local/ieternal/squid_cache/

/ usr/sbin/squid-k shutdown

/ usr/sbin/squid-z

# 4. Start

# / usr/sbin/squid

Service squid start

# 5. View listening port statu

Netstat-ntl

4. Set the yum proxy on the intranet machine

The code is as follows:

# execute on 191: set proxy

# agents for yum can be set separately

Vim / etc/yum.conf

# add at the end

Proxy= http://10.144.7.195:3128

# can also be executed in this way

# cp / etc/yum.conf / etc/yum.conf_original

# echo 'proxy= http://10.144.7.195:3128' > > / etc/yum.conf

# under the command line of Linux, general programs use the two environment variables http_proxy and ftp_proxy to obtain the agent settings.

# so you can use proxies as long as you use export http_proxy=10.144.7.195:3128.

# export http_proxy=10.144.7.195:3128

# if you want to set a system-level proxy, use the following statement:

# vim / etc/profile

# http_proxy= "10.144.7.195pur3128"

# export_http_proxy

The complete command is as follows:

The code is as follows:

Cp / root/.bash_profile / root/.bash_profile_bak_1231

Echo 'http_proxy=10.144.7.195:3128' > > / root/.bash_profile

Echo 'export http_proxy' > > / root/.bash_profile

Source / root/.bash_profile

Echo $http_proxy

At this point, you can use yum to install and update the software.

5. Use kill to kill some dead processes

The code is as follows:

# View processes with tomcat

Ps-aux | grep tomcat

# kill the specified process

# xxx is the process number seen

Kill-9 xxx

# restart tomcat

#......

6. The solution to the signature change of remote host

Because the 131server is reset, the remote host is prompted to change when logging in from linux again, with the following message:

The code is as follows:

[root@AY1312181745044978b4Z ~] # ssh 10.144.169.131

@ @ @

WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @

@ @ @

IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!

Someone could be eavesdropping on you right now (man-in-the-middle attack)!

It is also possible that the RSA host key has just been changed.

The fingerprint for the RSA key sent by the remote host is

36:86:33:b9:61:f8:fc:92:df:0b:d7:b3:ae:e5:4e:fb.

Please contact your system administrator.

Add correct host key in / root/.ssh/known_hosts to get rid of this message.

Offending key in / root/.ssh/known_hosts:2

RSA host key for 10.144.169.131 has changed and you have requested strict checking.

Host key verification failed.

In fact, you can know from the above information that / root/.ssh/known_hosts needs to be modified. The solution is to delete the row corresponding to this IP.

The mode of operation is to use vi or vim to open the file, then press ESC to enter command mode (if you press an or I to enter edit mode), and navigate to the line that needs to be deleted, press dd to delete a line.

The code is as follows:

Vim / .ssh/known_hosts

7. Install rzsz

In XShell or other ssh client tools, you can use rz to select file upload, or you can use sz to select file download. So it's a very useful tool.

The installation is simple:

The code is as follows:

Yum install lrzsz-y

Download file example:

The code is as follows:

Sz / etc/init.d/mysql

After executing this command, a dialog box pops up and the download starts after selecting the local storage path. However, there may be some delay in the display of the command line, so press enter again after the operation is completed.

As for the operation of rz, it is even easier, first cd to the path you need to upload, and then execute the rz command. Then also a pop-up dialog box, select file upload.

8. View disk space usage

The code is as follows:

# df-h

Filesystem Size Used Avail Use% Mounted on

/ dev/xvda1 20G 6.1G 13G 33% /

Tmpfs 939m 0939m 0% / dev/shm

/ dev/xvdb1 50G 21G 26G 45% / usr/local/ieternal

9. View the space size of the current directory

The code is as follows:

# du-ch-- max-depth=1

4.5G. / video_source

270M. / client

8.5G. / video

23M. / family

14M. / sid

341M. / repository

20M. / guide

127M. / style

1.5G. / photo

2.0G. / music

3.0G. / video_dest

21G.

21G total

-c is to do a statistical information at the end, and-h is to display manually readable statistics, such as 270m, 4.5G, etc. Maximum depth is set to 1. More options can be seen using "man du"

10. Install JDK

The code is as follows:

# View the available list

Yum list java*

# and then install JDK7,openJDK6 with bug, so.

Yum install java-1.7.0-openjdk*-y

Check to see if it is installed correctly:

The code is as follows:

# java-version

Java version "1.7.045"

OpenJDK Runtime Environment (rhel-2.4.3.4.el6_5-x86_64 u45-b15)

OpenJDK 64-Bit Server VM (build 24.45-b08, mixed mode)

# javac-version

Javac 1.7.0_45

11. Set up wget proxy

The code is as follows:

Echo 'https_proxy= http://10.144.7.195:3128/' > > $HOME/.wgetrc

Echo 'http_proxy= http://10.144.7.195:3128/' > > $HOME/.wgetrc

Echo 'ftp_proxy= http://10.144.7.195:3128/' > > $HOME/.wgetrc

twelve。 Install tomcat

The code is as follows:

# create a download directory

Mkdir / usr/local/ieternal/download

# enter the download directory

Cd / usr/local/ieternal/download

# download files

Wget http://mirror.bit.edu.cn/apache/tomcat/tomcat-6/v6.0.37/bin/apache-tomcat-6.0.37.tar.gz

# decompress the file

Tar-zxf apache-tomcat-6.0.37.tar.gz

# cut the directory

Mv apache-tomcat-6.0.37 / usr/local/tomcat

# enter the tomcat configuration directory

Cd / usr/local/tomcat/conf/

# back up the original configuration file

Cp-a / usr/local/tomcat/conf/server.xml / usr/local/tomcat/conf/server.xml_original

# Edit as needed

Vim / usr/local/tomcat/conf/server.xml

A complete example is as follows: two host domains are configured, including the default domain, and both the root directory and the upload directory are mapped to custom folders.

It should be noted that Chinese characters cannot exist by default, because the ANSI code is saved by default.

The code is as follows:

Localhost

Www.renfufei.cn

Renfufei.com

Renfufei.cn

M.renfufei.com

M.renfufei.cn

13. Install the FFMpeg transcoding program

FFMpeg is a powerful open source library that integrates the functions of playing, collecting input sources, decoding, transcoding, and audio and video servers. We are mainly used for transcoding.

To compile and install, you need to download the source code package, which is roughly as follows:

The code is as follows:

# on Tran1

First install the compilation environment.

Yum install-y automake autoconf libtool gcc gcc-c++

Yum install make

Download the required file ffmpeg.tar

Wget http://m.ieternal.com/upload/ffmpeg.tar

Decompress ffmpeg.tar

Tar xvf ffmpeg.tar

Change to the ffmpeg directory and execute the following command.

. / configure-prefix=/usr-disable-yasm

Make

Make install

Test the transcoding command and note that case-sensitive filenames include suffixes

Ffmpeg-I / usr/local/movi/qq.mov-r 25-b 3200k-vcodec mpeg4-ab 128k-ac 2-ar 44100 / usr/local/movi/kk.mp4.

The other is to use a compiled version that someone else has built, as follows:

The code is as follows:

#

# on Tran2.3.4:

# download directory: http://ffmpeg.gusari.org/static/64bit/

# 01-02 version: d1062ad9c208267241b6dfac7fa4ea25 (md5)

# create a directory and download

Mkdir / usr/local/ieternal/download

Mkdir / usr/local/ffmpeg

Cd / usr/local/ieternal/download

Wget http://ffmpeg.gusari.org/static/64bit/ffmpeg.static.64bit.2014-01-02.tar.gz

Mv / usr/local/ieternal/download/ffmpeg.static.64bit.2014-01-02.tar.gz / usr/local/ffmpeg/ffmpeg.tar.gz

Cd / usr/local/ffmpeg

# md5 check

Md5sum ffmpeg.tar.gz

# decompress to the current directory

Tar zxf ffmpeg.tar.gz

# set Path

Cp / root/.bash_profile / root/.bash_profile_bak_0102

Echo 'PATH=$PATH:/usr/local/ffmpeg' > > / root/.bash_profile

Echo 'export PATH' > > / root/.bash_profile

Source / root/.bash_profile

Echo $PATH

14. Start private network port forwarding

The code is as follows:

# 2. View IP and network card information

# it can be found that the address of eth0 is inet addr:10.144.7.195, which is a private network card.

# Public network card, the address of eth2 inet addr:115.28.9.136

# in addition, there is a loopback address, 127.*

Ifconfig

# 2.0 View Port occupancy

Netstat-ntl

# 2.1 View the existing iptables planning sets in the system

Iptables-- list-t nat

# 2.2 View the enabled status of IP forwarding

Cat / proc/sys/net/ipv4/ip_forward

# clear nat table

#-flush-F, Delete all rules

#-delete-chain-X, Delete a user-defined chain

#-zero-Z, Zero counters in chain or all chains

Iptables-F-t nat

Iptables-X-t nat

Iptables-Z-t nat

# enable IP packet forwarding, effective immediately

Echo 1 > / proc/sys/net/ipv4/ip_forward

# IP packet transfer, you can also set net.ipv4.ip_forward = 1

Vim / etc/sysctl.conf

# then the execution takes effect, and the restart is still valid

Sysctl-p

# Mapping port 3306 to 10.144.169.131purl 3306

# both PREROUTING and POSTROUTING must be set

# it has been tested and got through

Iptables-t nat-A PREROUTING-m tcp-p tcp-- dport 6606-j DNAT-- to-destination 10.144.169.131

Iptables-t nat-A POSTROUTING-j MASQUERADE

15. Compressed file

Package the blog directory under the current directory into a blog.tar.gz file:

The code is as follows:

Tar-zcf blog.tar.gz blog

Where-c means compression, compress;-z means zip compression;-f means output to a file (rather than output stream, memory, etc.); the following blog is the relative path, which can be multiple files / directories separated by spaces.

Naming .tar.gz is also a naming convention, and you can see at a glance that it is a gzip-compressed tar file.

If compression is not required, the command is as follows:

The code is as follows:

Tar-cf blog.tar blog

16. Extract the file

The corresponding directories are as follows:

The code is as follows:

Tar-zxf blog.tar.gz

If it is not gzip compression, it can be as follows:

The code is as follows:

Tar-xf blog.tar

17. NFS is easy to use

The code is as follows:

# Note: centos5 uses portmap

# yum install nfs-utils portmap

# centos6 uses rpcbind

# yum-y install nfs-utils rpcbind

NFS server

The code is as follows:

# install the package

Yum-y install nfs-utils rpcbind

# create a test directory

Cd / usr/local/

Mkdir / usr/local/nfstest

Mkdir / usr/local/nfstest/nfsdir

# add content

Echo "/ usr/local/nfstest 10.144.169.0 take 24 (rw,no_root_squash)" > > / etc/exports

Cat / etc/exports

Chkconfig nfs on

# start

/ etc/init.d/rpcbind start

/ etc/init.d/nfs start

NFS client

The code is as follows:

# install the package

Yum-y install nfs-utils rpcbind

Showmount-e 10.144.169.135

#

Cd / usr/local/

Mkdir / usr/local/nfstest

Mount-t nfs 10.144.169.135:/usr/local/nfstest/ / usr/local/nfstest/

Ll / usr/local/nfstest/

# set automatic loading, which needs to be written to / etc/fstab # I don't understand it yet

10.144.169.135:/usr/local/nfstest/ / usr/local/nfstest/ nfs nodev,ro,rsize=32768,wsize=32768 0 0

18. Set Nic information after virtual machine replication

After the VMware virtual machine is replicated, the network card information may not be loaded successfully.

The code is as follows:

Bringing up interface eth0: Device eth0 does not seem to be present,delaying initialization. [FAILED]

At this point, you need to modify the information in the / etc/sysconfig/network-scripts/ifcfg-eth0 file to avoid conflicts. The methods are as follows:

The code is as follows:

# cat / etc/udev/rules.d/70-persistent-net.rules

# This file was automatically generated by the / lib/udev/write_net_rules

# program, run by the persistent-net-generator.rules rules file.

#

# You can modify it, as long as you keep each rule on a single

# line, and change only the value of the NAME= key.

# PCI device 0x8086:0x100f (e1000)

SUBSYSTEM== "net", ACTION== "add", DRIVERS== "? *", ATTR {address} = = "00:0c:29:d7:b6:a9", ATTR {type} = = "1", KERNEL== "eth*", NAME= "eth0"

# PCI device 0x8086:0x100f (e1000)

SUBSYSTEM== "net", ACTION== "add", DRIVERS== "? *", ATTR {address} = = "00:0c:29:90:dd:db", ATTR {type} = = "1", KERNEL== "eth*", NAME= "eth2"

Check the physical hardware information first, and then write down the MAC address information of the eth2 Nic, such as "00:0c:29:90:dd:db"

Then modify the eth0 configuration script:

The code is as follows:

Vim / etc/sysconfig/network-scripts/ifcfg-eth0

The modified information is similar to the following. My virtual machine NAT here corresponds to the 192.168.254.* network segment. For specific network segment information, you can see the information of the network card "VMware Network AdapterVMnet8" of windows, or enter the ipconfig command under cmd to view it. 192.168.254.2 is the gateway of VMWARE. The address of automatic NAT. If you fail to check, please check the automatic DHCP information of VMWARE.

The code is as follows:

# cat / etc/sysconfig/network-scripts/ifcfg-eth0 "

DEVICE=eth2

HWADDR=00:0C:29:90:DD:DB

TYPE=Ethernet

UUID=cfb84a5c-c605-46ee-853c-214a7f4d7546

ONBOOT=yes

NM_CONTROLLED=yes

BOOTPROTO=static

IPADDR= "192.168.254.137"

NETMASK= "255.255.255.0"

GATEWAY= "192.168.254.2"

DNS1= "192.168.254.2"

Then, restart the network. In my case, it's a test that ping www.baidu.com works.

The code is as follows:

# restart the network

Service network restart

In addition, to solve the problem that the network of windows7 is very slow after installing VMWARE, you can go to Control Panel-> Network connection-> Local connection-> Properties-> Internet4 Settings-> Advanced-- > IP Settings-- > default gateway setting hops of 1.

19. Install rsync

Server side:

The code is as follows:

#

#

# # Server side

# installation

Yum-y install rsync xinetd

# start rsync dependency service

/ etc/init.d/xinetd start

Chkconfig xinetd on

Mkdir / usr/local/ieternal

Mkdir / usr/local/ieternal/upload

Mkdir / etc/rsyncd

# configuration file of rsync server

Touch / etc/rsyncd/rsyncd.conf

# File that defines server information

Touch / etc/rsyncd/rsyncd.motd

# user password file

Touch / etc/rsyncd/rsyncd.secrets

Chmod 600 / etc/rsyncd/rsyncd.secrets

# #

# #

Vim / etc/rsyncd/rsyncd.conf

The contents of the file / etc/rsyncd/rsyncd.conf are as follows: only one section of upload is defined, and subsequent client connections need to indicate that they are connected to this section.

The code is as follows:

Address=192.168.254.137

Port=873

Max connections=10

Uid=root

Gid=root

Use chroot=no

Strict modes=yes

Motd file = / etc/rsyncd/rsyncd.motd

Log format=%t a m f b

Syslog facility=local3

Timeout = 300

[upload]

Path=/usr/local/ieternal/upload/

Exclude = repository/

Comment = upload path

Ignore errors

Read only=no

List=yes

Auth users = rsync_user

Secrets file = / etc/rsyncd/rsyncd.secrets

Hosts allow=192.168.254.0/255.255.255.0

Hosts deny=*

Pid file = / var/run/rsyncd.pid

Lock file = / var/run/rsync.lock

Log file = / var/log/rsync.log

Specify the user and password, which is shown here:

The code is as follows:

# cat / etc/rsyncd/rsyncd.secrets

Rsync_user:pass_word

Welcome message:

The code is as follows:

# cat / etc/rsyncd/rsyncd.motd

Services user=rsync_user;pass_word=***

Start the rsync service

The code is as follows:

# start the rsync service:

/ usr/bin/rsync-daemon-config=/etc/rsyncd/rsyncd.conf

# View port status

Netstat-ntl

Client:

The code is as follows:

# 1. Installation

Mkdir / usr/local/ieternal

Mkdir / usr/local/ieternal/upload

Mkdir / etc/rsyncd

Yum-y install rsync xinetd

# 2. Start the rsync dependency service

/ etc/init.d/xinetd start

Chkconfig xinetd on

# 3. Client must configure password file

Touch / etc/rsync.pas

Chmod 600 / etc/rsync.pas

Vim / etc/rsync.pas

Specify the password:

The code is as follows:

# cat / etc/rsync.pas

Pass_word

Perform synchronization:

The code is as follows:

# 4. Perform synchronization

# download:

Rsync-auzv-- progress-- delete-- password-file=/etc/rsync.pas rsync_user@192.168.254.137::upload / usr/local/ieternal/upload

# upload:

Rsync-auzv-- progress-- delete-- password-file=/etc/rsync.pas / usr/local/ieternal/upload/* rsync_user@192.168.254.137::upload

Error message:

The code is as follows:

Rsync: failed to connect to 192.168.254.137: No route to host

Rsync error: error in socket IO (code 10) at clientserver.c [receiver=3.0.6]

It has been found that it is caused by the opening of the firewall, and you can modify the firewall filtering rules or deactivate the firewall on the client and server:

The code is as follows:

# stop the firewall

Service iptables stop

20. IO monitoring tools

Installation:

The code is as follows:

Yum-y install iotop

Use

The code is as follows:

# iotop

The general summary information is as follows: disk read and write speed

The code is as follows:

Total DISK READ: 0.00Bamp s | Total DISK WRITE: 0.00BUnip s

21. Install memcached

If you do not have gcc, you need to install:

The code is as follows:

# install gcc

Yum-y install gcc

Install dependent library libevent::

The code is as follows:

# install dependent library libevent

Yum-y install libevent libevent-devel

Download the package at the reference address: http://memcached.org/

The code is as follows:

# download

Mkdir / usr/local/ieternal

Mkdir / usr/local/ieternal/download

Cd / usr/local/ieternal/download

Wget http://www.memcached.org/files/memcached-1.4.17.tar.gz

Check the download package:

The code is as follows:

# calculate the sha1 value

# Hash check tool included with linux: sha1sum or md5sum

# 2b4fc706d39579cf355e3358cfd27b44d40bd79c

Sha1sum memcached-1.4.17.tar.gz

Decompress:

The code is as follows:

# decompression

Tar zxf memcached-1.4.17.tar.gz

Installation:

The code is as follows:

# installation

# by default, memcached is installed in the / usr/local/bin/ directory

Cd memcached-1.4.17

. / configure

Make

Make install

Start at the front desk:

The code is as follows:

# / usr/local/bin/memcached-p 11211-m 64m-vv-u root

/ usr/local/bin/memcached-u root

Start at the background:

The code is as follows:

# start at backend

#-h displays only help information

#-u root specifies to run as a user

#-p TCP port number

#-m maximum memory size, default is 64m

#-vv starts in very verbose mode, and debug information and errors are output to the console

#-d starts in the background as a daemon

/ usr/local/bin/memcached-p 11211-m 64m-d-u root

Use the pid file at startup to write the process ID to a specific file:

The code is as follows:

# background startup, port number, memory, user, pid file

/ usr/local/bin/memcached-d-p 11211-m 128m-u root-P / usr/local/memcached.pid

Ps aux | grep memcached

Cat / usr/local/memcached.pid

# Kill process, note that it is not a single quotation mark, but the character before the number 1 on the keypad `

Kill `cat / usr/local/ Memcached.pid`

twenty-two。 Generate key pairs using GPG

The code is as follows:

# install GnuPG, that is, GPG, which is generally included in the system

Yum install gpgme-y

# View help information

Gpg-help

# generate key.

Gpg-gen-key

23. Apache Bench benchmark test

Apache Bench, referred to as ab, is a stress benchmark tool that comes with the Apache server. Mode of use:

The code is as follows:

/ usr/local/apache2/bin/ab-c 10-t 10 http://www.baidu.com/

Where-c refers to concurrency, that is, the number of concurrent threads, and-t refers to time in seconds. Test Baidu for 10 seconds and use 10 client threads.

Another commonly used parameter is-n, that is, the total number of limit tests is how many times, if multiple parameters are combined, the condition that should be met first will become a limit.

Of course, the full path is used above, please decide according to the installation path. You can also enter the bin directory of apache first:

The code is as follows:

Cd / usr/local/apache2/bin/

# Test 100 times

. / ab-c 10-n 100 http://www.baidu.com/

It is also used in the same way under windows, except that the path is different.

Of course, you can also output the results to a file in HTML format:

The code is as follows:

. / ab-c 10-t 10-w http://www.baidu.com/ > > / usr/local/ab_20140311204010.log.html

The detailed help information is as follows:

The code is as follows:

[root@ALY bin] # cd / usr/local/apache2/bin/

[root@ALY bin] #. / ab-h

How to use:. / ab [options] [http://]hostname[:port]/path

Options include:

-n the number of requests to be executed by requests

-c how many concurrent threads does concurrency build to execute

-t timelimit maximum limit time (in Second, seconds). When the time is up, you will wait for the response to complete before exiting.

-buffer size sent / received by b windowsize TCP protocol, in byte

-p postfile POST requests the data to be sent. Need to set option-T

-u putfile PUT requests the data to be sent. Need to set option-T

-content format header information (Content-type) sent by T content-type, for example

'application/x-www-form-urlencoded' et al.

The default value is' text/plain'

-v troubleshooting log information level that verbosity needs to print

-w print result information using HTML tables format

-I request using HEAD instead of GET

-x attributes to insert the string as table attributes

-y attributes to insert the string as tr attributes

-z attributes to insert the string as td/th attributes

-C attribute adds cookie information, for example: 'Apache=1234. (multiple available)

-H attribute add arbitrary header information (header line), for example: 'Accept-Encoding: gzip'

Insert after other normal header information. (can be more than one)

-An attribute adds basic website authentication information (Basic WWW Authentication)

The attribute uses a colon (:) to separate username from password.

-P attribute add proxy user password (Basic Proxy Authentication)

The attribute uses a colon (:) to separate username from password.

-the proxy server to be used by X proxy:port and the port number

-V only prints the version number and exits

-k uses the HTTP KeepAlive feature

-d do not display response time statistics percentage.

-S do not show trust estimates (? Confidence estimators) and warning messages.

-g filename outputs the collected data to an Gnuplot interactive drawing format file.

-e filename outputs the response time statistics percentage to the CSV file

-r Don't quit when socket accepts an error.

-h displays help information (this is actually the message)

24. Time synchronization

The synchronization time can be accomplished by executing the following command using root:

The code is as follows:

Rdate-s time.nist.gov

If you need automatic synchronization, you can use crontab automatic scheduling, which is performed once an hour:

Edit crontab:

The code is as follows:

Crontab-e

Press I to enter insert mode, and then add the following line:

The code is as follows:

1 * root rdate-s time.nist.gov

Then press ESC to enter the command mode. After seeing the colon, enter wq and enter to save and exit (actually vi / etc/crontab).

The answers to the questions about the use of server management in Linux are shared here. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel for more related knowledge.

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