Sometime you want to know what .so libraries are used by a program. Let's say that the program's binary is in /bin/prog. $ ldd /bin/prog will do the trick. Except it doesn't capture everything. Sometimes you need to examine the running program. Let's say you wish to find out what process 123 has loaded at this time. $ pmap 123 -p or $ lsof -p 123 (The -p in each command means something different.) In each case, look for lines with the string ".so".