astronemo is the name you may find in some package managers. If you google the name nemo, you will find a lot of computer related tools with that name. We also adopted this name in https://astronemo.readthedocs.io.
NEMO is a Stellar Dynamics Toolbox for users and programmers. It has various programs to create, integrate and analyze N-body systems. In addition there are various tools to operate on images, tables and orbits, including FITS files to export/import to/from other astronomical data reduction packages.
A good start is the manual page programs(8NEMO) , which lists programs thematically, and index(1NEMO) , which lists them alphabetically (CAVEAT: these pages are not well maintained).
NEMO is very much modeled after the Unix(tm) operating system, so users are expected to use standard Unix commands as glue between the various tasks (cat, ls, rm, cp, awk, sm, etc.). Understanding of shell scripting (sh, csh, python, perl, etc.) can be very useful. for NEMO as well. Several example shell scripts exist in the source tree to demonstrate how experiments can be orchestrated. We use mostly csh, bash and python. Yes, csh too, even though csh is considered harmful now.
Here are some useful reminders of using NEMO when you are familiar with the unix style of command line tools, piping etc.:
- programs use a set of key=value command line arguments,
minimum match works, but you cannot repeat keywords
* the --help or help=h are ways to get inline help from a program
and remind you of the keyword names
* keyword values can be math expressions (see nemoinp(1NEMO))
* the UNIX man(1) command will get offline help
- NEMO can use pipes efficiently:
* The UNIX stdin and stdout are represented with a dash (-),
so using pipes can become a little awkward
* The UNIX /dev/null is represented with a dot (.),
like a black hole sucking up everything
apropos keyword
man -M $NEMO/man -k .
man -f keyword also: program help=u
man --regex <pattern> man --regex ".*network$"
man -S <section_ID> <keyword>
man -wK <keyword>
program --help program --man program help=h program [key1=]val1 [key2=]val2 .!.!. runprogram [key1=]val1 [key2=]val2 .!.!. run program ...
The easiest way is to add the appropriate line to your .cshrc or .bashrc file, but you need to know the root directory where NEMO is installed. For example
source /opt/nemo/nemo_start.sh
or for (t)csh users we still have
source /opt/nemo/nemo_start.csh
If you need more control over your NEMO environment, there are other methods described elsewhere (The NEMO Users/Programmers Guide, Appendix A), or consult one of your local friendly NEMO users.
For systems where this is supported, the module(1) command may be able to load nemo, e.g.
module load nemo
module load nemo/4.2.1
mkplummer - 10 | snapprint -
this would be identical to the two liner
mkplummer out=p10.snap nbody=10
snapprint in=p10.snap
NEMO programs all work by using a series of keyword=value pairs on the commandline. If the order of the supplied keywords is the same as the program expects them, the keyword= part can be omitted, simply to save some keystrokes. There is a consistent ordering of keywords in most programs that allows experienced users to use such (and other) shortcuts. Python uses the same principle with the un-named arguments. (e.g. in= the first one, out= the second one etc.). Keywords can be used in minimum match, but this is not recommended for shell scripts. To make shell scripts robust, it is recommended you add the keyword= part for all but the first one or two.
NEMO programs make a distinction between program keywords (keywords unique to a program) and system keywords (a fixed set of keywords that each NEMO program understands). The system keywords that you are likely to use are help= and yapp=, and to a lesser degree debug= and error=. The help= gives various types of inline aid from a program. There is also online help on a program, for which unix man(1) command (or any of it’s derived friends) is normally used. The yapp= sets the graphics device used by programs who use a graphics device. Your nemo_start environment may have given you a default. YAPP=/xs is a common default if the yapp_pgplot interface is used.
Each system keyword can be defaulted by setting it’s equivalent environment variable (in upper case!). Program keywords can be abbreviated to uniqueness.
Examples: Consider the program mkplummer, a program which creates an N-body realization of a Plummer sphere. To get online help, one types (we included three legacy program options, --man, --help, --version):
man mkplummer
mkplummer --man
and to get various types of inline help:
mkplummer --help
mkplummer -h
mkplummer help=
mkplummer help=h
mkplummer help=’?’
and to get the version:
mkplummer help=V
mkplummer --version
Note the literal quotes around the question-mark needed if you use a regular
Unix shell as interface. The first help= reminds you of the order of the
program keywords and their default values. The second form, help=h prints
out a small one-line reminder what each keyword means. The last form help=’?’
lists various options the user interface understands, this one is not program
dependant.
If you chain NEMO programs, pipes can be a very efficient way to stream data and/or prevent large amounts of disk access. Most keywords that operate on files (notably in=, out=, as long as stropen(3NEMO) is used) can use standard piped I/O by using the dash (-) to name the keyword, e.g.
mkplummer - 10 | snapprint -
would create a snapshot of 10 bodies on the fly, and print positions and velocities to the user using snapprint. The alternative would have been
mkplummer out=tmp nbody=10
snapprint in=tmp
rm tmp
Over the times NEMO has incoorporated a number of non-NEMO programs, with varying degrees of input parameter schemes. Some via parameter files, some interactive input, some a command line interface alien to NEMO. For a number of them a unified NEMO frontend was developed, usually those programs start with the prefix run. For example, bulgerot comes with runbulgerot. Since often such programs have a hardcoded name for input and/or output files, one simple way to be able to run them in parallel without stepping on filenames, is the use of a clean run directory. Example of this can be found in runbulgerot(1NEMO) , runbody1(1NEMO) , rungalaxy(1NEMO) , runscfm(1NEMO) , runqumond(1NEMO) , and some others.
You will find a few common user keywords for this: outdir= is always a required keyword, and needs to be a non-existing directory in which the data is written. For some programs there is an exe= keyword, in order to change the name of the non-NEMO program to be run. This is always assumed to be in the standard Unix search path ($PATH).
Although these run* programs use a fairly common method to run the non-NEMO programs, they have not all been unified as is proposed in run(3NEMO) .
man -l $MIRDOC/man/man1/potfft.1
more $gip_root/tsk/potential.dc1
https://www.unix.com/man-page-repository.php - Man Page Repository https://man7.org/linux/man-pages/man1/man.1.html - The Linux man-pages project
Various man(1NEMO) pages explain programs(1) , subroutine libraries(3) file formats(5) and system management(8) .
NEMO homepage http://www.astro.umd.edu/nemo and github page https://github.com/teuben/nemo.
readthedocs page: https://astronemo.readthedocs.io/en/latest/ (this replaced the old latex manual)
Other introductions
Workshop on N-body simulations: \ http://paginapessoal.utfpr.edu.br/rubensmachado/outros-1/simulacoes-de-n-corpos/NbodyTutorial.pdf
is always https://github.com/teuben/nemo/issues
1986 V1 Initial Development Barnes/Hut/Teuben 1994 V2 UMD release Teuben 2001 V3 UMD release using CVS Teuben 2017 V4 UMD release using git Teuben