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cpcapundefined-reference
Anastasiya Stoyka
Anastasiya Stoyka

Reputation: 13

proj.c:(.text+0x140): undefined reference to `pcap_open_offline'

I'm trying to use pcap functions, but it giving me compiler error:

project.c:(.text+0x140): undefined reference to `pcap_open_offline'

I have installed library and while compiling I give "-lpcap" at the and as it advised in many forums.

What can be wrong, please?

Upvotes: 0

Views: 1627

Answers (1)

user4207183
user4207183

Reputation:

You need to understand what the arguments evoke into the linker.

I am supposing you are using Linux system with gcc, using ld as linker (note that this could change depending on the system and the linker used).

In such case, -Lpath tell the linker where to look for the libraries that you tell it that are needed to be linked with your program to create the final binary. For example -L/usr/lib.

when you type in for example:

# gcc -L/usr/lib -lcap my_program.c -o my_program

You are telling the linker to append /usr/lib to the list of paths to locate libraries, and to link the dynamic library "libcap.so" with your program.

Other modifiers for the path used to locate libraries is LD_LIBRAY_PATH (the name of this environment variable could change from one system to another, review the manual of your linker).

As you are using "-lcap" the error you get look to be related with the fact that no path is found where libcap.so exist. Locate that file into your system and pass the argument

-L/path/to/the/directory/that/contain/libcap.so

By the way, try to run this before any other thing and recompile:

# sudo ldconfig

Upvotes: 1

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