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Online Help for the LAMMPS Shell App

This page provides documentation and additional files to download for use with the LAMMPS Shell. The downloads are especially aimed at users that have installed LAMMPS on Windows 10 through Microsoft Store, since those are lacking those files. The alternative would be to download "complete" installer packages, however those are not cryptographically signed. Those usually require administrator privileges to install and are the only option when you want to use an MPI parallel version.


Please see the online version of the LAMMPS manual for documentation of the LAMMPS software itself.


The following archives are available for download:


Overview

The LAMMPS Shell, lammps-shell is a program that functions very similar to the regular LAMMPS executable but has several modifications and additions that make it more powerful for interactive sessions, i.e. where you type LAMMPS commands from the prompt instead of reading them from a file.

These enhancements makes the LAMMPS shell an attractive choice for interactive LAMMPS sessions in graphical desktop environments (e.g. Gnome, KDE, Cinnamon, XFCE, Windows).


TAB-expansion

When writing commands interactively at the shell prompt, you can hit the TAB key at any time to try and complete the text. This completion is context aware and will expand any first word only to commands available in that executable.


Command line editing and history

When typing commands, command line editing similar to what BASH provides is available. Thus it is possible to move around the currently line and perform various cut and insert and edit operations. Previous commands can be retrieved by scrolling up (and down) or searching (e.g. with CTRL-r).

Also history expansion through using the exclamation mark "!" can be performed. Examples: "!!" will be replaced with the previous command, "!-2" will repeat the command before that, "!30" will be replaced with event number 30 in the command history list, and "!run" with the last command line that started with run. Adding a ":p" to such a history expansion will result that the expansion is printed and added to the history list, but NOT executed. On exit the LAMMPS shell will write the history list to a file .lammps_history in the current working directory. If such a file exists when the LAMMPS shell is launched it will be read to populate the history list.

This is realized via the readline library and can thus be customized with an .inputrc file in the home directory. For application specific customization, the LAMMPS shell uses the name "lammps-shell". For more information about using and customizing an application using readline, please see the available documentation at: http://www.gnu.org/s/readline/#Documentation


Additional commands

The following commands are added to the LAMMPS shell on top of the regular LAMMPS commands:

help (or ?)    print a brief help message
history        display the current command history list
clear_history  wipe out the current command history list
save_history <range> <file>
               write commands from the history to file.
               The range is given as <from>-<to>, where <from> and <to>
               may be empty. Example: save_history 100- in.recent
source <file>  read commands from file (same as "include")
pwd            print current working directory
cd <directory> change current working directory (same as pwd if no directory)
mem            print current and maximum memory usage
|<command>     execute <command> as a shell command and return to the command prompt
exit           exit the LAMMPS shell cleanly (unlike the "quit" command)

Please note that some known shell operations are implemented in the LAMMPS shell command in a platform neutral fashion, while using the "|" character will always pass the following text to the operating system's shell command.


Readline customization

The behavior of the readline functionality can be customized in the ${HOME}/.inputrc file. This can be used to alter the default settings or change the key-bindings. The LAMMPS Shell sets the application name lammps-shell, so settings can be either applied globally or only for the LAMMPS shell by bracketing them between

$if lammps-shell
# disable "beep" or "screen flash"
set bell-style none
# bind the "Insert" key to toggle overwrite mode
"\e[2~": overwrite-mode
$endif

More details about this are in the readline documentation.


LAMMPS Shell tips and tricks

Enable tilde expansion

Adding set expand-tilde on to ${HOME}/.inputrc is recommended as this will change the filename expansion behavior to replace any text starting with "~" by the full path to the corresponding user's home directory. While the expansion of filenames will happen on all arguments where the context is not known (e.g. ~/compile/lamm<TAB> will expand to ~/compile/lammps/), it will not replace the tilde by default. But since LAMMPS does not do tilde expansion itself (unlike a shell), this will result in errors. Instead the tilde-expression should be expanded into a valid path, where the plain "~/" stands for the current user's home directory and "~someuser/" stands for "/home/someuser" or whatever the full path to that user's home directory is.

File extension association

Since the LAMMPS shell (unlike the regular LAMMPS executable) does not exit when an input file is passed on the command line with the "-in" or "-i" flag (the behavior is like for python -i <filename>), it makes the LAMMPS shell suitable for associating it with input files based on their filename extension (e.g. ".lmp"). Since lammps-shell is a console application, you have to run it inside a terminal program with a command line like this:

xterm -title "LAMMPS Shell" -e /path/to/lammps-shell -i in.file.lmp

Use history create input file

When experimenting with commands to interactively to figure out a suitable choice of settings or simply the correct syntax, you may want to record part of your commands to a file for later use. This can be done with the save_history commands, which allows to selectively write a section of the command history to a file (Example: save_history 25-30 in.run). This file can be further edited (Example: |vim in.run) and then the file read back in and tried out (Example: source in.run). If the input also creates a system box, you first need to use the clear command command.


Last modified: Sat Oct 17 02:33:02 UTC 2020 by akohlmey