# jump command

## Syntax

    jump file label

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

## Examples

    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 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.

    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 -in command-line argument or the -var command-line argument to pass the script name as a variable to the input script In the latter case, the “fname” variable could be used in place of SELF. E.g.

    lmp_g++ -in in.script

    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 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.

    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.

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

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

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

    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

    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

variable, include, label, next

Default: none