The units database includes many units, and it can sometimes
be difficult to remember every name.
The interactive search command examines only unit names, so it
cannot be used to find units whose definitions contain a pattern.
If units is invoked with the --list-units option, the
output can be sent to a filter such as grep, examining the
unit name and the definition. For example,
units --list-units | grep ';' dms deg;arcmin;arcsec ftin ft;in;1|8 in ftin16 ft;in;1|16 in ftin32 ft;in;1|32 in ftin4 ft;in;1|4 in ftin64 ft;in;1|64 in ftin8 ft;in;1|8 in hms hr;min;sec inchfine in;1|8 in;1|16 in;1|32 in;1|64 in time year;day;hr;min;sec uswt lb;oz . . .
could find all unit lists, which include at least one semicolon in their definitions.
The search command
doesn’t support regular expressions, but with the
--list-units option the output can be sent to a filter such as
grep, which does. If you expect a long list of results, you
can send the output of the filter to a pager. For example,
units --list-units | grep 'paper[[:space:]]' | more A0paper 841 mm 1189 mm A10paper 26 mm 37 mm A1paper 594 mm 841 mm A2paper 420 mm 594 mm A3paper 297 mm 420 mm A4paper 210 mm 297 mm A5paper 148 mm 210 mm A6paper 105 mm 148 mm A7paper 74 mm 105 mm A8paper 52 mm 74 mm A9paper 37 mm 52 mm . . .
could show a list of all defined paper sizes.