How to tell if a running program is 64-bit in Linux

ping needs root so it can open a socket in raw mode. That's literally the first thing it does when it starts up:

icmp_sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
socket_errno = errno;

That's the only thing it needs root for, so like many programs, it immediately drops its privilege level back to your normal user account:

uid = getuid();
if (setuid(uid)) {
    perror("ping: setuid");
    exit(-1);
}

With regard to eclipse not being able to find adb, etc, this because without the 32-bit shared libraries needed to run them on the system, they are not executable.

With regard to 32-bit libraries, the situation is fairly simple: you just need to install the appropriate 32-bit libs. On the 64-bit fedora 17 install I have here, the primary 64-bit libraries are in /usr/lib64 and optional 32-bit libs are in /usr/lib. So, if I call ldd on on sdk/platform-tools/adb:

linux-gate.so.1 =>  (0xf7791000)
librt.so.1 => /lib/librt.so.1 (0xf776c000)
libncurses.so.5 => /lib/libncurses.so.5 (0xf7747000)
libpthread.so.0 => /lib/libpthread.so.0 (0xf772d000)
libstdc++.so.6 => /lib/libstdc++.so.6 (0xf7644000)
libm.so.6 => /lib/libm.so.6 (0xf7618000)
libgcc_s.so.1 => /lib/libgcc_s.so.1 (0xf75fb000)
libc.so.6 => /lib/libc.so.6 (0xf7449000)
/lib/ld-linux.so.2 (0xf7792000)
libdl.so.2 => /lib/libdl.so.2 (0xf7444000)
libtinfo.so.5 => /lib/libtinfo.so.5 (0xf7424000)

Notice these are all in /lib, which is a symlink to /usr/lib (not /usr/lib64). Look:

»file /lib/libc.so.6
/lib/libc.so.6: symbolic link to `libc-2.15.so'
»file /lib/libc-2.15.so
/lib/libc-2.15.so: ELF 32-bit LSB shared object [...]

A 32-bit standard C library. What you can do is go through the 32-bit sdk tools and check to see what they are linked against with ldd. I don't have an example at hand, but if something is missing ldd reports something like:

libc.so.6 => ??????

First, tho, for ldd to work you will need the 32-bit loader that comes with the 32-bit glibc (without this, ldd will call it a non-executable file and tell you nothing):

»yum search glibc
glibc.i686 : The GNU libc libraries
glibc.x86_64 : The GNU libc libraries

That's truncated, but the x86_64 package is what you have already; the i686 is the 32-bit version. So just install that.

You do not need any of the 'devel' packages, as nothing gets compiled. Beyond that, educated guesses and yum whatprovides / yum search should help (looking at the list for adb, there's also 32-bit versions of the C++ lib, ncurses, pthreads, and a I few things I don't know).

Quick tip about using whatprovides:

»yum whatprovides libtinfo
No matches found.
»yum whatprovides libtinfo.so.5
[2 matches]
»yum whatprovides "*/libtinfo.so.5"
[4 matches]

;)