From Open Babel
|Chemical MIME Type||Undefined|
|Open Babel Version||2.0.0 and later|
Objects can be chemically filtered without the risk of losing any additional information they contain, since no format conversion is done. Note that XML files may be missing non-object elements at the start or end and so may no longer be well-formed.
Extract only structures that include at least one aromatic carbon (by matching the SMARTS pattern '[c]')
babel -s '[c]' database.sdf -ocopy new.sd