csvtool: add page (#4391)

pages/common/csvtool.md

@@ -0,0 +1,24 @@
+# csvtool
+
+> Utility to filter and extract data from CSV formatted sources.
+> More information: <https://github.com/maroofi/csvtool>.
+
+- Extract the second column from a CSV file:
+
+`csvtool --column {{2}} {{path/to/file.csv}}`
+
+- Extract the second and fourth columns from a CSV file:
+
+`csvtool --column {{2,4}} {{path/to/file.csv}}`
+
+- Extract lines from a CSV file where the second column exactly matches 'Foo':
+
+`csvtool --column {{2}} --search '{{^Foo$}}' {{path/to/file.csv}}`
+
+- Extract lines from a CSV file where the second column starts with 'Bar':
+
+`csvtool --column {{2}} --search '{{^Bar}}' {{path/to/file.csv}}`
+
+- Find lines in a CSV file where the second column ends with 'Baz' and then extract the third and sixth columns:
+
+`csvtool --column {{2}} --search '{{Baz$}}' {{path/to/file.csv}} | csvtool --no-header --column {{3,6}}`