JSON行からフラグメントを抽出する

かなり長いJSON行（〜1.5KB）が複数あります。おそらく次のようになります。 "XYZ":{"myString":"myValue",ABCD}

行全体から「myString」：「myValue」を抽出したいと思います。 grep自体はすべて1行にあり、greptoの出力をパイプしたいのですが、awk区切り文字が必要に応じて動作しないようですので、私には役立ちません。誰でも助けることができますか？

この文書は単なるJSON文書ではありません。ファイルには多くのコンテンツがあり、その一部はmyValue（myStringの一部として）を抽出したいJSON行です。例は次のとおりです。

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