Editing UPU (section)

== USAGE ==

'''Example #1''' (level 1)
 upu '{cartesian;ls;save;export xsf}' ''/path/to/''CONTCAR
The command proceeds the following steps: reads a CONTCAR file, switches easily from the default direct coordinates to Cartesian, prints this half-edited version of CONTCAR to the the <TT>stdout</TT>, saves it the modification (output file "CONTCAR"), exports and  saves the supercell to the XCrysDen format (output file "CONTCAR.xsf") and quits to BASH shell.

'''Example #2''' (level 2)
 upu '{cartesian ;\
       measure distance a 0 a 1 ;\
       measure angle a 0 a 1 a 2 ;\
       measure dihedral a 0 a 1 a 2 a 3
       }' ''/path/to/''CONTCAR
The command reads in a stucture-*CAR file, and measures the distance between atoms # 1 and 2, the bond angle between the atoms # 1-2-3 and the dihedral angle on the atoms # 1-2-3-4. 

Each ''measure''ment has a one-line numerical output, thus it is easy to be parsed. So if the output of the <TT>upu</TT> command is redirected into a file ("<TT>upu '{commands}' CONTCAR > data.dat</TT>"), you can easily parse the variable in a BASH-script using e.g.
 tail -3 data.dat > temp.dat
 for i in `seq 1 3` ; do
  var[$i]=`awk -v line=$i '(NR==line){print $1}' temp.dat`
 done