print command

Syntax

print string keyword value

• string = text string to print, which may contain variables

• zero or more keyword/value pairs may be appended

• keyword = file or append or screen

  file value = filename
  append value = filename
  screen value = yes or no
  

Examples

print "Done with equilibration" file info.dat
print Vol=$v append info.dat screen no
print "The system volume is now $v"
print 'The system volume is now $v'
print """
System volume = $v
System temperature = $t
"""

Description

Print a text string to the screen and logfile. The text string must be a single argument, so if it is one line but more than one word, it should be enclosed in single or double quotes. To generate multiple lines of output, the string can be enclosed in triple quotes, as in the last example above. If the text string 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 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 and screen = yes.