[Tips] How to quickly locate a shared library under Linux __linux

In some cases, you might want to know which directory my program links to.

There are three ways to deal with this easily.

1. LDD command

$ LDD App

2. Static Lookup

$ locate Lib_name

3. Dynamic implementation

$ strace App 2>&1 | grep lib_name

Let me give you an example.

Ubuntu's 64-bit LS is linked to the Libselinux.so.1 library.

So we're going to find out where this library is.

1. ldd

$ ldd/bin/ls

Libselinux.so.1 =>/lib64/libselinux.so.1 (0x00007f97dd5a9000)

In addition, if LDD finds a library that is not found, you can use Ldd-r to print out specific symbols.

Like what:

# ldd-r/test.
Linux-vdso.so.1 => (0x00007fff8a32b000)
Libfoo.so => not found
Libc.so.6 =>/lib64/libc.so.6 (0x00007fef5bfa9000)
/lib64/ld-linux-x86-64.so.2 (0x00007fef5c352000)
Undefined Symbol:foo (./test)

2. Static Lookup

$ locate Libselinux.so.1

/lib/i386-linux-gnu/libselinux.so.1
/lib/x86_64-linux-gnu/libselinux.so.1

We can see that there are two positions, one is the bit and the other is the bit.

Because we know that LS is 64 bits, the corresponding library should be:/lib/x86_64-linux-gnu/libselinux.so.1

3. Dynamic implementation

$ strace ls 2>&1 | grep libselinux.so.1

Open ("/lib/x86_64-linux-gnu/libselinux.so.1", o_rdonly| O_CLOEXEC) = 3

Through open this system call we know the use is:/lib/x86_64-linux-gnu/libselinux.so.1