Edit with sed using capturing group of curly braces (windows)-CodePudding

On Windows, I am trying to do an in-place edit of simple JSON files that are malformed. My files look like this, with first object duplicated.

{
  "hello":"there"
}
{
  "hello":"there"
}

My goal is to have only one object, and discard the second one. I should note that the files have linefeeds, as shown here. End file should look like

{
  "hello":"there"
}

I can match the first group using a regexp like ^({.*?}).*. This is fairly simple.

Seems like a perfect job for sed in-place editing. But apparently no matter what combination of escaping I do in sed, I can't match the brackets. I am using (GNU sed) 4.9 patch by Michael M. Builov.

Some results I get:

# as per original regexp
sed.exe -E "s,^({.*?}).*,d,g" double.json
     ->  -e expression #1, char 16: Invalid preceding regular expression

# trying to escape paranthesis
sed.exe -E "s,^\({.*?}\).*,d,g" double.json
     ->  -e expression #1, char 18: Invalid content of \{\}

# escaping curly brackets
sed.exe -E "s,^\(\{.*?\}\).*,d,g" double.json
     -> Works, but original file is returned (no match)

Is it possible at all on Windows ? According to this and this comment it seems that Windows for some reason does not like curly brackets with sed.

Note: tested in WSL/Ubuntu, and got same result.

CodePudding user response：

You can try this GNU sed

$ sed -Ez 's/((\{[^}]*}).*)\2/\1/' input_file
{
  "hello":"there"
}

CodePudding user response：

jq command line tool is handy to use for JSON values, even on Windows. You can download by this link as an example.

Then save the command

inputs

into a file called double.jq, and then call from command line by

[Windows key] cmd

cd to_the_path_where_the_files_reside    
jq -f double.jq <double.json

if there are more than two independent objects within the file double.json such as

{
  "hello":"there"
}
{
  "hello":"there"
}
{
  "hello":"there"
}
{
  "hello":"there"
}

and want to pick the first one only, then convert code of the double.jq to

[inputs] | unique | .[]