Sort text file of blocks

Question

There are plenty of tools that will sort a text file on the assumption that the unit of interest is the line, but are there any that work on blocks?

Example:

name = Mercury
order = 1
mass = 0.06

name = Venus
order = 2
mass = 0.82

name = Earth
order = 3
mass = 1

Is there a tool that would sort the list of planets optionally by name, mass or order from the sun, taking as input and producing as output a text file with each record being a block like the above?

Answer 1

For files that fit into memory you could use Perl, you can define the input record separator.

 perl -e '$/="\n\n"; print sort <>' t.txt

If the file is too big for memory but you have an equal amount of free disk space, you can do a three step sort:

• use perl to merge lines of each record
• sort
• use perl to split lines of each record

To sort by the value of one of the attributes, I would read the data into a suitable data structure such as an array of hashes AoH and define a comparator as described in perldoc -f sort

Alternatively I would

• Use perl to convert to CSV of values only
• sort
• Use perl to convert CSV back to multiline records with name=value pairs

It would probably be best to do the whole job in Perl.

Other programming languages are available.