chem

groff preprocessor for chemical structure diagrams

TLDR

Process a chem file and view the output

$ chem [path/to/file.chem] | groffer

Process and convert to PostScript

$ chem [path/to/file.chem] | groff -p -Tps > [output.ps]

Process from stdin

$ echo '.cstart\nCH3\nbond\nCH3\n.cend' | chem | groffer

Display version information

$ chem --version

SYNOPSIS

chem [option...] [--] [filespec...]chem -h | --helpchem -v | --version

chem is a groff preprocessor for producing chemical structure diagrams. It translates chemical notation into pic language diagrams, which can then be processed by groff for rendering.The tool is best suited for organic chemistry, supporting bonds, rings, moieties (like CH3, NH3), and strings. Chemical diagrams are enclosed between .cstart and .cend markers.Example input:

$ .cstart
CH3
bond
CH3
.cend

Since chem is a pic preprocessor, raw pic statements can be included within diagrams for custom drawings.

PARAMETERS

-h, --help

Display usage message and exit

-v, --version

Display version information and exit

filespec

Input file or - for stdin. Without arguments, reads stdin

INSTALL

sudo apt install groff

sudo dnf install groff

sudo pacman -S groff

sudo apk add groff

sudo zypper install groff

brew install groff

nix profile install nixpkgs#groff

CAVEATS

No library or file inclusion mechanism exists. No shorthand for repetitive structures. The extension mechanism uses pic macros, which can be tricky to implement correctly.There is no in-line chemistry syntax (like eqn's $...$ construct) and no way to control bond entry points on groups.

HISTORY

The GNU version of chem was written by Bernd Warken, based on documentation of Brian Kernighan's original awk version. The chemical structure diagram language was developed at Bell Labs alongside other troff preprocessors like eqn and pic.

RESOURCES

Source code · Homepage