How to sort text by section and also sort lines under the section in linux?

Question

I have a text config file which is like this:


config server 'server'
        option url 'https://chef.libremesh.org'

config client 'client'
        option upgrade_packages '1'
        option auto_search '0'
        option advanced_mode '0'

I want the output to be like this:


config client 'client'
        option advanced_mode '0'
        option auto_search '0'
        option upgrade_packages '1'

config server 'server'
        option url 'https://chef.libremesh.org'

Which command to use ?

William Pursell · Accepted Answer · 2021-06-16 17:00:03Z

1

My perl is a bit rusty, so this can certainly be made cleaner. Try:

perl -nE 'BEGIN{$/=""}; @b = split "\n", $_; 
    @a = shift @b; push @a, sort @b; 
    push @f, join("\n", @a); END{ say "$_\n" foreach sort @f }' input

Set $/ to the empty string so that perl reads each section as a record. The initial split splits each record on the newlines, and then we construct the array @a by shifting off the first line of the section and then sorting the remaining lines. Construct a string from that and push it onto the array @f. At the end, sort the sections and write output.

You can trim a bit by autosplitting:

perl -F'\n' -a -nE 'BEGIN{$/=""}; 
    push @f, join "\n", shift @F, sort @F;
    END{ say "$_\n" foreach sort @f } ' input

or:

perl -00 -F'\n' -a -nE 'push @f, join "\n", shift @F, sort @F} 
    {print join "\n\n", sort @f' input

The last command is a somewhat weird idiom which takes advantage of the fact that -n puts the command inside an implicit while(<>){...} construct and the first } in the code matches the implicit { while the "unmatched" { matches the implicit }, making it similar to running the final code in an END block.

edited Jun 16, 2021 at 17:00

answered Jun 16, 2021 at 15:57

William Pursell

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3 Comments

SSAnkur Over a year ago

This works great. But it removes the empty lines at the beginning, ending and between the sections. Is it possible to do it without removing the empty lines ?

William Pursell Over a year ago

Ah, yes, those are important. Will fix.

William Pursell Over a year ago

I think you can get what you need by just doing say "$_\n" to add an extra newline after each record.

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