how do I select an atom using pymol?

I'm not sure if this is the right web page 开发者_StackOverflow中文版to ask...

I have a xyz file I have generated:

   C   0   0   0
   O   0   0   0.1
   O   0   0   0.2
   C   0   0   0.6
   O   0   0   0.5
   O   0   0   0.4
   .
   .
   .

How can I select a specific atom in command line or measure the distance between two atoms (pymol)?

pymol select command is described in detail here: http://www.pymolwiki.org/index.php/Property_Selectors

In your case, to select certain atom(s), you can use:

select C_atoms, name C # select all C atoms and name the selection C_atoms
select atom_4, id 4    # select the 4th atom in the file and name it atom_4
select idx_4, index 4  # 
select rank_4, rank 4  # 

as for the difference between rank, ID, index for atoms, see

http://www.mail-archive.com/pymol-users@lists.sourceforge.net/msg08503.html

I have sent an email to the pymol email-list. I need to find the ID of the atom/molecule I want (I'm sure there is a better way but I have used the gui interface) and then:

select id <num>

or

distance id<num>, id<num>

to measure distance