#pragma weak means that even if the definition of the symbol is not found, no error will be reported.
Example
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
#include<stdio.h>
// It is not an error for symbol to never be defined at all. // Without this line, the address of "foo" will always evaluate to "true", // so the linker will report an "undefined reference to 'foo'" error. #pragma weak foo // The declaration is needed. /* extern */voidfoo();
npm root - Current installation root path. npm root -g - The global installation root path. npm uninstall - After executing this command, you should also remove the items in the package.json file and delete the package-lock.json file and the node_modules directory.
The link-local address range refers to IP addresses that are used for communication within a single network segment or link. These addresses are not routable, meaning they are not intended to be used for communication beyond the local network segment.
For IPv4, the link-local address range is 169.254.0.0/16. This range is automatically assigned to network interfaces when no other IP address is available (e.g., when DHCP fails). Devices on the same local network can communicate with each other using these addresses without requiring a router.
For IPv6, the link-local address range is fe80::/10. These addresses are automatically configured on all IPv6-enabled interfaces and are used for local network communication.
The IP address range 169.254.0.0/16 is regarded as link-local because it is reserved for link-local addresses by the Internet Assigned Numbers Authority (IANA). These addresses are used for communication within a single network segment or link and are not routable beyond that segment.
Characteristics of Link-Local Addresses:
Automatic Assignment: Devices automatically assign themselves an IP address from the 169.254.0.0/16 range if they cannot obtain an IP address through DHCP.
Non-Routable: These addresses are not meant to be routed across different network segments. They are only valid within the local network.
Zero Configuration: Link-local addresses allow devices to communicate without manual configuration or a DHCP server.
Example: When a device fails to get an IP address from a DHCP server, it might assign itself an address like 169.254.1.2. Other devices on the same local network segment will also have addresses in the 169.254.0.0/16 range, allowing them to communicate directly.
命令
ip
NAME
ip - show / manipulate routing, devices, policy routing and tunnels.
1 2 3
$ ip route get 8.8.8.8 8.8.8.8 via 192.168.1.1 dev eth0 src 192.168.1.100 uid 1000 cache
说明：
8.8.8.8: The destination IP address for which the route is being queried.
via 192.168.1.1: The gateway IP address through which the destination can be reached.
dev eth0: The network interface (e.g., eth0) used to reach the destination.
src 192.168.1.100: The source IP address used for sending packets to the destination.
uid 1000: The user ID of the process that issued the command.
cache: Indicates that the route information is cached.
1 2 3 4
$ ip route show default via 192.168.1.1 dev eth0 192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.100 169.254.0.0/16 dev idrac proto kernel scope link src 169.254.1.2
说明：该命令用于显示路由表：
default via 192.168.1.1 dev eth0: The default route, packets to any destination not in the routing table will be sent to 192.168.1.1 via the eth0 interface.
192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.100: A route for the 192.168.1.0/24 network (destination network), directly reachable via the eth0 interface, with the source IP 192.168.1.100.
-n, --numberic
-l, --listening
-t, --tcp
Note: Only established (non-listening) connections.
-a, --all
Display both listening and non-linstening (for TCP this means established connections) sockets.
-u, --udp
-p, --process
lsof
Options:
-n inhibits the conversion of network numbers to host names for network files.
-P inhibits the conversion of port numbers to port names for network files.
-i specifies the Internet addresses
multiple addresses (up to a limit of 100) may be specified with multiple options.
An Internet address is specified in the form (Items in square brackets are optional.):
[46][protocol][@hostname|hostaddr][:service|port]
where:
46 specifies the IP version, IPv4 or IPv6
that applies to the following address.
'6' may be be specified only if the UNIX
dialect supports IPv6. If neither '4' nor
'6' is specified, the following address
applies to all IP versions.
protocol is a protocol name - TCP, UDP
hostname is an Internet host name. Unless a
specific IP version is specified, open
network files associated with host names
of all versions will be selected.
hostaddr is a numeric Internet IPv4 address in
dot form; or an IPv6 numeric address in
colon form, enclosed in brackets, if the
UNIX dialect supports IPv6. When an IP
version is selected, only its numeric
addresses may be specified.
service is an /etc/services name - e.g., smtp -
or a list of them.
port is a port number, or a list of them.
-s list file size
-s p:s exclude(^)|select protocol (p = TCP|UDP) states by name(s).
Phoenix turned and fired twice, the 34 millimetre bullets spitting through the air and splintering the brickwork two inches to the left of the Russia thug’s shoulder. A moment later came the reply of the Uzi semiautomatic and Phoenix twisted round. 菲尼克斯转身开了两枪，34毫米的子弹在空中喷射，将俄罗斯暴徒肩膀左侧两英寸砖墙击碎。过一会儿，乌兹半自动冲锋枪回应了，菲尼克斯扭过身来。
Her lips, searching in the sapphire, honeyscented darkness, found his; cool, forceful, unresisting, and as the frozen waves crashed down. 当冰冷、有力、不可抗拒的浪汹涌而下的时候，她的嘴唇在蓝宝石般散发着蜜香的夜色中寻找，找到了他的嘴唇。
-Got your meeting, have you? 你要去开会，对吗？ -Yes, I’m on my way. 是的，我正在去。
He pulled her towards him, his powerful, masculine hands tearing at the silk faric of her Gaultier nightshirt.
The repetitive beat of the innercity drum.
1887, Sebastian Lyddiard, greatgrandson of Herbert Lyddiard, who served under Sir John Jervis against Napoleon. 对抗拿破仑。
The Right Honourable William Lyddiard. 威廉·利迪亚德阁下。
-Do you ever regret marrying hime, Amy? I wonder if you ever think that but for you he might still be alive? 你后悔嫁给他吗，埃米？我不知道你是否想过，如果不是因为你，他可能现在还活着？ -(Amy) No. 没有想过。 -Well I do. 我想过。
-So we come to the question of which writer we invite to address us? 所以我们打算请哪位作家来给我们做演讲呢？ -How about Jilly Cooper? -I think he said a writer. -Do you think we could interest Frederick Forsythe? -I rather doubt it. -Oh, it’s a wonderful idea, Gerald. Especially since you’re writing a thriller. I think Frederick Forsythe would be first rate! 我认为Frederick Forsythe是第一流的。 -He’d never come. He’d just pretend he didn’t have time. They always do. -I’d like Seamus Heaney. -The poet? -Not another poet. That last one was such a ghastly little man.
词汇
screenplay by 剧本由……写成 millimetre 毫米 phoenix 凤凰，这里是人名，菲尼克斯 spit 吐，唾 thug 恶棍，暴徒 twist 扭，拧，捻 brickwork 砖砌体，砖墙 splinter n. 碎片，弹片； v. 碎裂。 Uzi semiautomatic 乌兹半自动冲锋枪（Uzi submachine gun）。Uzi 冲锋枪是由以色列国防军 (IDF) 上尉（后来的少校）Uziel Gal 在 1948 年阿以战争后设计的。 sapphire 蓝宝石 honey 蜂蜜，蜜 scent 香味（a pleasant natural smell）；scented 散发香味的 resist 抗拒的；unresisted 不可抗拒的。 masculine 男性的。 tear 撕，撕破，撕毁；拆；泪水。 nightshirt 睡衣 scum 浮渣 scum-bag 渣子袋，这里应该是“渣男”、“人渣”的意思，骂人的话。 hum 哼声 greatgrandson 曾孙 Sir 爵士 Napoleon 拿破仑 The Right Honourable 阁下。其中，Right是副词，意思是’very’ or ‘fully’。从语法上说，The Right Honourable 是形容短语，直接用来称呼人名或者某人用来自称都是不正确的，应该与其引用的名称或名称一起使用第三人称。 address 演讲 first rate 第一流 pretend 假装 ghastly US:/ˈɡæst.li/ UK:/ˈɡɑːst.li/ 阴森的，可怕的，非常坏的 bestseller 畅销书