jq: add page (#1092)

pages/common/jq.md

@@ -0,0 +1,27 @@
+# jq
+
+> A lightweight and flexible command-line JSON processor.
+
+- Output JSON file:
+
+`cat {{file}} | jq`
+
+- Output all elements from JSON array in file, or all key-value pairs from JSON objects in file:
+
+`cat {{file}} | jq .[]`
+
+- Read JSON objects from file, into array, and output (inverse of `jq .[]`):
+
+`cat {{file}} | jq --slurp`
+
+- Output first element in JSON file:
+
+`cat {{file}} | jq .[0]`
+
+- Output "key" of first element in JSON file:
+
+`cat {{file}} | jq .[0].{{key}}`
+
+- Output "key" of each element in JSON file:
+
+`cat {{file}} | jq 'map(.{{key}})'`