print command — LIGGGHTS v3.X documentation

# print command

## Syntax

print string keyword value:pre

- string = text string to print, which may contain variables
- zero or more keyword/value pairs may be appended

    keyword = file or append or screen or newline:l
      file value = filename
      append value = filename
      screen value = yes or no
      newline value = yes or no

## Examples

    print "Done with equilibration" file info.dat
    print Vol=$*volume* append info.dat screen no newline no
    print "The system volume is now $v"
    print 'The system volume is now $v'

## Description

Print a text string to the screen and logfile. One line of output is generated. The text string must be a single argument, so it should be enclosed in double quotes if it is more than one word. If it contains variables, they will be evaluated and their current values printed.

If the file or append keyword is used, a filename is specified to which the output will be written. If file is used, then the filename is overwritten if it already exists. If append is used, then the filename is appended to if it already exists, or created if it does not exist.

If the screen keyword is used, output to the screen and logfile can be turned on or off as desired.

If the newline keyword is used and its value set to no then no newline character will be printed at the end of the string. This can be useful if a string should be concatenated.

If you want the print command to be executed multiple times (with changing variable values), there are 3 options. First, consider using the fix print command, which will print a string periodically during a simulation. Second, the print command can be used as an argument to the every option of the run command. Third, the print command could appear in a section of the input script that is looped over (see the jump and next commands).

See the variable command for a description of equal style variables which are typically the most useful ones to use with the print command. Equal-style variables can calculate formulas involving mathematical operations, atom properties, group properties, thermodynamic properties, global values calculated by a compute or fix, or references to other variables.

## Restrictions

> none

## Related commands

fix print, variable

## Default

The option defaults are no file output, screen = yes and newline = yes.