Yrurtj

I'm using sed and I am having trouble finding out how to remove some of the first line of text from each block. Here is my original data:

  "s220823vaps2512":   {

"hostname": "s220823vaps2512",

"description": data",

"type": "Virtual",

"os": "data",

"idc": "data",

"environment": "data",

"deviceclass": "data",

"cores": "data",

"memory": "data",

"frontnet": "data",

"ipset":     {

  "backnet": "data",

  "storagenet": "data",

  "metroclusternet": "data"

},

"roles": "data",

"mounts": "data"

  },

   "s220823vaps2513":   {

"hostname": "s220823vaps2513",

"description": "data",

"type": "Virtual",

"os": "data",

"idc": "data",

"environment": "data",

"deviceclass": "data",

"cores": "data",

"memory": "data",

"frontnet": "data",

"ipset":     {

  "backnet": "data",

  "storagenet": "data",

  "metroclusternet": "data"

},

I want to use sed to successfully remove everything up until the { on the first line of each block leaving me with a data format similar to

{

 "hostname": "data",

  "etc": "etc",

},

{

 "hostname": "data",

  "etc": "etc",

},

This answer is predicated on the above looking rather a lot like JSON, so I've therefore assumed it probably is JSON. But it's incomplete in your sample, which I have also assumed is a typo. If this isn't the case... well, you already have sed answers.

Please - don't use a regex to parse JSON. It's nasty. regex is bad at recursive tagged data types like JSON/XML. It's at best a dirty hack which creates brittle code in future.

Similarly - JSON is important that it be complete - I've had to guess how your full JSON looks.

Assuming JSON like this (used http://jsonlint.com/ to tidy up the elements)

{

    "s220823vaps2512": {

        "hostname": "s220823vaps2512",

        "description": "data",

        "type": "Virtual",

        "os": "data",

        "idc": "data",

        "environment": "data",

        "deviceclass": "data",

        "cores": "data",

        "memory": "data",

        "frontnet": "data",

        "ipset": {

            "backnet": "data",

            "storagenet": "data",

            "metroclusternet": "data"

        },

        "roles": "data",

        "mounts": "data"

    },

    "s220823vaps2513": {

        "hostname": "s220823vaps2513",

        "description": "data",

        "type": "Virtual",

        "os": "data",

        "idc": "data",

        "environment": "data",

        "deviceclass": "data",

        "cores": "data",

        "memory": "data",

        "frontnet": "data",

        "ipset": {

            "backnet": "data",

            "storagenet": "data",

            "metroclusternet": "data"

        }

    }

}

Then the way to just get the bits you want:

#!/usr/bin/env perl

use strict;

use warnings;



use JSON;



my $input = ### as above, snipped for brevity. 



#decode/validated

my $json = decode_json ( $input );

#create new JSON array of elements. 

my $new_json = [map { $json -> {$_} } keys %$json];

#print it out. 

print to_json ( $new_json, { pretty => 1, canonical => 1 } );

And in this way, you create valid JSON output as well as handling cases where e.g. key ordering is different (which is entirely valid in JSON).

Simple with sed:

sed 's/^[^{]*{/{/' file

• Just searches for lines starting with characters which are not { (^[^{]), zero or more times * followed by a {.


• This all is replaced by a single {.

Edit: If you want to exclude some patterns from being replace (for example the "ipset": line) use this:

sed '/"ipset":/n;s/^[^{]*{/{/' file

• If the line starts with "ipset":, continue with the next line n.

This seems to work, at least on the sample of data you provided:

sed -'s/^ .*{/{/' file 

It transforms the first line of each block "name" { (note the leading space) to just {