.. index:: jump

jump command
============

Syntax
""""""

.. parsed-literal::

   jump file label

* file = filename of new input script to switch to
* label = optional label within file to jump to

Examples
""""""""

.. parsed-literal::

   jump newfile
   jump in.run2 runloop
   jump SELF runloop

Description
"""""""""""

This command closes the current input script file, opens the file with
the specified name, and begins reading LIGGGHTS(R)-PUBLIC commands from that file.
Unlike the :doc:`include <include>` command, the original file is not
returned to, although by using multiple jump commands it is possible
to chain from file to file or back to the original file.

If the word "SELF" is used for the filename, then the current input
script is re-opened and read again.

.. warning::

   The SELF option is not guaranteed to work when the
   current input script is being read through stdin (standard input),
   e.g.

.. parsed-literal::

   lmp_g++ < in.script

since the SELF option invokes the C-library rewind() call, which may
not be supported for stdin on some systems.  This can be worked around
by using the :ref:`-in command-line argument <start_7>` or
the :ref:`-var command-line argument <start_7>` to pass
the script name as a variable to the input script In the latter case,
the "fname" :doc:`variable <variable>` could be used in place of SELF.
E.g.

.. parsed-literal::

   lmp_g++ -in in.script

.. parsed-literal::

   lmp_g++ -var fname n.script < in.script

The 2nd argument to the jump command is optional.  If specified, it is
treated as a label and the new file is scanned (without executing
commands) until the label is found, and commands are executed from
that point forward.  This can be used to loop over a portion of the
input script, as in this example.  These commands perform 10 runs,
each of 10000 steps, and create 10 dump files named file.1, file.2,
etc.  The :doc:`next <next>` command is used to exit the loop after 10
iterations.  When the "a" variable has been incremented for the tenth
time, it will cause the next jump command to be skipped.

.. parsed-literal::

   variable a loop 10
   label loop
   dump 1 all atom 100 file.$a
   run 10000
   undump 1
   next a
   jump in.lj loop

If the jump *file* argument is a variable, the jump command can be
used to cause different processor partitions to run different input
scripts.  In this example, LIGGGHTS(R)-PUBLIC is run on 40 processors, with 4
partitions of 10 procs each.  An in.file containing the example
variable and jump command will cause each partition to run a different
simulation.

.. parsed-literal::

   mpirun -np 40 lmp_ibm -partition 4x10 -in in.file

.. parsed-literal::

   variable f world script.1 script.2 script.3 script.4
   jump $f

Here is an example of a double loop which uses the :doc:`if <if>` and
jump commands to break out of the inner loop when a condition is met,
then continues iterating thru the outer loop.

.. parsed-literal::

   label	    loopa
   variable    a loop 5
     label	    loopb
     variable  b loop 5
     print	    "A,B = $a,$b"
     run       10000
     if	    $b > 2 then "jump in.script break"
     next	    b
     jump	    in.script loopb
   label	    break
   variable    b delete

.. parsed-literal::

   next	    a
   jump	    in.script loopa

Restrictions
""""""""""""


If you jump to a file and it does not contain the specified label,
LIGGGHTS(R)-PUBLIC will come to the end of the file and exit.

Related commands
""""""""""""""""

:doc:`variable <variable>`, :doc:`include <include>`, :doc:`label <label>`,
:doc:`next <next>`

**Default:** none


.. _liws: http://www.cfdem.com
.. _ld: Manual.html
.. _lc: Section_commands.html#comm