PyMOL>cd /
PyMOL>pwd
/
PyMOL>cd $PYMOL_PATH/test
PyMOL>ls
  CVS      TODO     dat      ref      show     trim.py  win.py 
  README   cmp      inp      run      tmp      vdiff  
PyMOL>ls *.py
  trim.py  win.py 
PyMOL>ls no_files
 ls: Nothing found.  Is that a valid path?
PyMOL>ls *no_files
 ls: Nothing found.  Is that a valid path?
PyMOL>system
Parsing-Error: missing required argument: command
PyMOL>system echo "hello"
hello
PyMOL>system ls
cmp
CVS
dat
inp
README
ref
run
show
tmp
TODO
trim.py
vdiff
win.py
