Makefile specifies the path of the library file loaded when the program runs

1 Problem description

Program runtime , Prompt library not found .
reason ： The default library path to run and load is /usr/lib

2 resolvent

2.1 Method 1 , Set up PATH environment variable

How to join these paths ？ With PATH Variables, for example .
One way is ： Directly under the command line ：
$PATH="$PATH:/path/to/your/bin:/another/path/to/bin”
$ export PATH
The advantage of this method is convenience , Immediate effect , The disadvantage is to put the current session or shell It will fail after it is closed , I have to run it again next time .

2.2 Method 2 , modify makefile, Specify the path directly

The other way is ：makefile Add the library file path of the running program
LDFLAGS+= -Wl,-Bstatic -lbt
LDFLAGS+= -Wl,-rpath=/opt/lib/
LDDIR+=-Lhost/libbt/lib
CC=/opt/toolchain/arm-2012.03/bin/arm-none-linux-gnueabi-gcc

Compile instructions ：
$(CC)$(LDDIR) -o $@$^ $(LDFLAGS)

3 makefile Description of relevant parameters

CFLAGS For C Compiler options ,
CXXFLAGS For C++ Compiler options .
These two variables actually cover compilation and assembly .
Let's start with a few related environment variables ：PATH、LDFLAGS、CFLAGS

LDFLAGS：gcc Wait for some optimization parameters that the compiler will use , You can also specify the location of the library file in it . usage ：LDFLAGS=“-L/usr/lib -L/path/to/your/lib”. Every installation of a package will almost certainly create one in the installation directory lib Catalog . If you install a package , When you install another package , It said it couldn't find , Then take that bag lib Path joined LDFALGS Have a try .

CFLAGS： and LDFLAGS similar , Just add the header file to it （.h file ） The path of , Such as ：CFLAGS=“-I/usr/include -I/path/to/your/include”. similarly , When a package is installed, a include Catalog , When there is a problem during the installation , Try to install the package before include The directory is added to the variable .