1.12.网络命令
1.12.1.write
给指定用户发信息，以Ctrl+D保存结束并发送
以root用户给test用户发条信息
[root@localhost cn]# write test
i missing you.
[root@localhost cn]#
test收到的消息
[test@localhost ~]$
Message from [email protected] on pts/0 at 21:58 ...
i missing you.
EOF
该命令发消息时，用户必须在线才能发，否则发出去的。
可以使用w看有哪些用户在线
1.12.2.wall
英文愿意：write all
发广播消息
语法：wall [message]
发送后，自己收到一份
[root@localhost cn]# wall hello world!
[root@localhost cn]#
Broadcast message from [email protected] (pts/0) (Fri Apr 27 22:01:56 2018):
hello world!
test用户也收到一份
Broadcast message from [email protected] (pts/0) (Fri Apr 27 22:01:56 2018):
hello world!
1.12.3.ping
测试网络连通性
ping 选项 IP地址
-c 指定发送次数
默认不会停止，一直发送数据包，必须Ctrl+C才能结束
[root@localhost cn]# ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.913 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=1.54 ms
64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=0.804 ms
64 bytes from 192.168.1.1: icmp_seq=4 ttl=64 time=0.797 ms
^C
--- 192.168.1.1 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9006ms
rtt min/avg/max/mdev = 0.735/0.947/1.542/0.225 ms
packet loss 丢包率，看以判断网络质量。
使用-c选项，指定发送次数
[root@localhost cn]# ping -c 2 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.856 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.874 ms
--- 192.168.1.1 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 0.856/0.865/0.874/0.009 ms
[root@localhost cn]#
1.12.4.ifconfig
英文原意：interface configure
查看和设置网卡信息
语法：ifconfig 网卡名称 IP地址
查看网卡
[root@localhost cn]# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.200 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::87e1:e178:41b3:d5b1 prefixlen 64 scopeid 0x20<link>
ether 00:15:5d:01:65:06 txqueuelen 1000 (Ethernet)
RX packets 4592 bytes 859283 (839.1 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1655 bytes 160274 (156.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1 (Local Loopback)
RX packets 5 bytes 560 (560.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 5 bytes 560 (560.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo回环网卡
RX packets 接收数据包及大小
TX packets 发送数据包及大小
设置IP，临时更改，非永久修改
范例：
ifconfig eth0 192.168.1.202
1.12.5.mail
查看发送电子邮件
这个比write好的是，不需要用户必须在线。
以Ctrl+D保存结束并发送邮件
mail命令的使用需要安装mailx安装包
[root@localhost cn]# yum install mailx
给root用户发送一封邮件
[root@localhost cn]# mail root
Subject: test subject
hi.
EOT
查看发送的邮件
[root@localhost cn]# mail
Heirloom Mail version 12.5 7/5/10. Type ? for help.
"/var/spool/mail/root": 1 message 1 new
>N 1 root Fri Apr 27 22:18 18/610 "test subject"
N表示未读
1 表示邮件的ID
root 是发送用户
发送时间
邮件标题
进入邮件查看交互命令下，以&开头命令
输入help
可以查看命令帮助
& help
mail commands
type <message list> type messages
next goto and type next message
from <message list> give head lines of messages
headers print out active message headers
delete <message list> delete messages
undelete <message list> undelete messages
save <message list> folder append messages to folder and mark as saved
copy <message list> folder append messages to folder without marking them
write <message list> file append message texts to file, save attachments
preserve <message list> keep incoming messages in mailbox even if saved
Reply <message list> reply to message senders
reply <message list> reply to message senders and all recipients
mail addresses mail to specific recipients
file folder change to another folder
quit quit and apply changes to folder
xit quit and discard changes made to folder
! shell escape
cd <directory> chdir to directory or home if none given
list list names of all available commands
A <message list> consists of integers, ranges of same, or other criteria
separated by spaces. If omitted, mail uses the last message typed.
&
输入邮件ID 1查看邮件内容
& 1
Message 1:
From [email protected] Fri Apr 27 22:18:17 2018
Return-Path: <[email protected]>
X-Original-To: root
Delivered-To: [email protected]
Date: Fri, 27 Apr 2018 22:18:17 +0800
Subject: test subject
User-Agent: Heirloom mailx 12.5 7/5/10
Content-Type: text/plain; charset=us-ascii
From: [email protected] (root)
Status: R
hi.
&
输入h回到邮件列表
邮件看过后，N就没有显示了
& h
> 1 root Fri Apr 27 22:18 18/610 "test subject"
&
输入d 邮件ID，删除邮件
& d 1
& h
No applicable messages
&
输入q退出
& q
[root@localhost cn]#
1.12.6.last
列出目前与过去所有登入系统的用户信息，还包括系统重启
[root@localhost cn]# last
用户 登录终端 登录的IP登录时间是否还在线/退出时间、持续时间
test pts/1 192.168.1.101 Fri Apr 27 21:57 still logged in
root pts/0 192.168.1.101 Fri Apr 27 21:20 still logged in
reboot system boot 3.10.0-693.el7.x Fri Apr 27 19:50 - 22:28 (02:37)
test pts/1 192.168.1.101 Thu Apr 26 23:22 - 23:22 (00:00)
test pts/1 192.168.1.101 Thu Apr 26 23:07 - 23:22 (00:15)
reboot system boot 3.10.0-693.el7.x Wed Apr 25 21:43 - 22:28 (2+00:45)
root pts/0 192.168.1.101 Tue Apr 24 20:19 - crash (1+01:23)
wtmp begins Sun Apr 22 16:10:16 2018
用户列为reboot时，表示系统重启了。
1.12.7.lastlog
最后一次登录信息
列出所有的用户信息，列出最后一次登录信息
[root@localhost cn]# lastlog
Username Port From Latest
root pts/0 192.168.1.101 Fri Apr 27 21:20:22 +0800 2018
bin **Never logged in**
daemon **Never logged in**
adm **Never logged in**
lp **Never logged in**
sync **Never logged in**
shutdown **Never logged in**
halt **Never logged in**
mail **Never logged in**
operator **Never logged in**
games **Never logged in**
ftp **Never logged in**
nobody **Never logged in**
systemd-network **Never logged in**
dbus **Never logged in**
polkitd **Never logged in**
postfix **Never logged in**
sshd **Never logged in**
test pts/1 192.168.1.101 Fri Apr 27 21:57:39 +0800 2018
-u 用户ID 查看某个用户的登录信息
[root@localhost cn]# lastlog -u 0
Username Port From Latest
root pts/0 192.168.1.101 Fri Apr 27 21:20:22 +0800 2018
[root@localhost cn]# lastlog -u 1000
Username Port From Latest
test pts/1 192.168.1.101 Fri Apr 27 21:57:39 +0800 2018
如何查看用户ID？
[root@localhost cn]# cat /etc/passwd
root:x:0:0:root:/root:/bin/bash
1.12.8.traceroute
显示数据包到主机间的路径
该命令需要安装包traceroute
[root@localhost cn]# yum install traceroute
[root@localhost cn]# traceroute www.baidu.com
traceroute to www.baidu.com (119.75.213.61), 30 hops max, 60 byte packets
1 gateway (192.168.1.1) 0.525 ms 0.503 ms 1.113 ms
2 * * *
3 * * *
4 10.144.11.202 (10.144.11.202) 1.729 ms 1.720 ms 1.709 ms
5 14.197.242.145 (14.197.242.145) 4.232 ms * 4.900 ms
6 14.197.248.253 (14.197.248.253) 7.647 ms 14.197.248.241 (14.197.248.241) 5.957 ms 14.197.248.253 (14.197.248.253) 6.582 ms
7 14.197.252.197 (14.197.252.197) 45.213 ms 14.197.252.189 (14.197.252.189) 44.424 ms 14.197.252.37 (14.197.252.37) 45.195 ms
8 14.197.252.54 (14.197.252.54) 45.174 ms 45.180 ms 14.197.252.50 (14.197.252.50) 45.170 ms
9 14.197.149.178 (14.197.149.178) 45.162 ms 14.197.149.182 (14.197.149.182) 41.744 ms *
10 * * *
11 * 182.61.253.126 (182.61.253.126) 53.336 ms 42.238 ms
12 * * *
13 * * *
14 * * *
15 * * *
16 * * *
17 * * *
18 * * *
19 * * *
20 * * *
21 * * *
22 * * *
23 * * *
24 * * *
25 * * *
26 * * *
27 * * *
28 * * *
29 * * *
30 * * *
1.12.9.netstat
net status网络状态
显示网络相关的信息
-t TCP协议，有握手，确定接收到。
-u UDP协议，不握手，直接丢个信息过去，不管你接到不接到
-l 监听
-r 路由
-n 显示IP地址和端号
范例：
netstat –tlun 查看本机监听的端口
[root@localhost cn]# netstat -tlun
Active Internet connections (only servers)
协议 接收传输距离，0表示正常
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN
tcp6 0 0 :::22 :::* LISTEN
tcp6 0 0 ::1:25 :::* LISTEN
[root@localhost cn]#
TCP才有监听LISTEN，UDP不会有
netstat –an 查看本机所有的网络连接
-a all的意思
[root@localhost cn]# netstat -an
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN
tcp 0 0 192.168.1.200:22 192.168.1.101:52591 ESTABLISHED
tcp 0 36 192.168.1.200:22 192.168.1.101:51745 ESTABLISHED
tcp 0 0 192.168.1.200:22 192.168.1.101:52592 ESTABLISHED
tcp 0 0 192.168.1.200:22 192.168.1.101:51748 ESTABLISHED
tcp6 0 0 :::22 :::* LISTEN
tcp6 0 0 ::1:25 :::* LISTEN
raw6 0 0 :::58 :::* 7
Active UNIX domain sockets (servers and established)
Proto RefCnt Flags Type State I-Node Path
unix 2 [ ACC ] STREAM LISTENING 19078 public/flush
unix 2 [ ACC ] STREAM LISTENING 19093 public/showq
ESTABLISHED 已经连接状态
netstat –rn 查看本机路由表
可以查看到网关地址
[root@localhost cn]# netstat -rn
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
[root@localhost cn]#
1.12.10.setup
配置网络
red hat 自带的管理工具集合，在其他版本Linux中不存在。
可以支持：
防火墙配置
网络配置
系统服务
验证配置
安装setuptool
[root@localhost cn]# setup
-bash: setup: command not found
[root@localhost cn]# yum install setuptool
Loaded plugins: fastestmirror
直接输入setup命令，即可进入配置工具
[root@localhost cn]# setup
1.12.11.mount
挂载
mount [-t 文件系统] 设备文件名 挂载点
挂载光盘
mount –t iso9660 /dev//sr0 /mnt/cdrom
iso9660
表示的光盘文件系统，这个固定的。系统就知道，实事上可以不写。
设备文件名，固定的，光盘就是/dev/sr0，也可以指定为软链接/dev/cdrom
[root@localhost dev]# ll /dev/cdrom
lrwxrwxrwx. 1 root root 3 Apr 27 23:11 /dev/cdrom -> sr0
1、安装光盘
2、创建挂载点
[root@localhost /]# mkdir /mnt/cdrom
3、挂载
[root@localhost dev]# mount /dev/cdrom /mnt/cdrom
mount: /dev/sr0 is write-protected, mounting read-only
[root@localhost dev]#
提示信息表示光盘是只读，被近挂载为只读文件
进入挂载点就可以访问了，/dev/cdrom是设备，是进不去的，不能访问
[root@localhost dev]# cd /mnt/cdrom
[root@localhost cdrom]# ls
autorun.inf boot bootmgr bootmgr.efi efi setup.exe sources support upgrade
[root@localhost cdrom]#
4、卸载
Linux中你挂载使用中，必须自己手动卸载
在挂载点目录时，卸载不了，如下提示：需要退出挂载点目录
[root@localhost cdrom]# umount /mnt/cdrom
umount: /mnt/cdrom: target is busy.
(In some cases useful info about processes that use
the device is found by lsof(8) or fuser(1))
[root@localhost cdrom]#
卸载以后，目录/mnt/cdrom就什么内容没有了。
卸载时，可以指定挂载点，还可以指定设备：umount /dev/sr0
[root@localhost /]# umount /mnt/cdrom
[root@localhost /]# ls /mnt/cdrom
[root@localhost /]#