xidel:tldr:12509

The given command is using the tool called "xidel" to extract relevant information from a webpage. Here's a breakdown of the command:

• xidel: It is the name of the command-line tool that is being executed.
• ${https:--www-google-com-search?q=test}: This is the URL of the webpage you want to fetch and analyze. In this case, it is pointing to a Google Search page with the query parameter "test".
• --extract: It is an argument for xidel that specifies which information to extract from the webpage.
• "//a/extract(@href, 'url[?]q=([^&]+)&', 1)[. != '']": This is an XPath expression that instructs xidel on how to extract information. The XPath expression has several components:
  • //a: Selects all <a> tags (links) in the webpage.
  • extract(@href, 'url[?]q=([^&]+)&', 1): Extracts a portion of the href attribute of each link using a regular expression.
  • The regular expression 'url[?]q=([^&]+)&' captures the value of the query parameter q in the URL.
  • The 1 is the capture group index (specified as 1) which fetches the captured value.
  • [. != '']: Filters out empty values. So, only non-empty values, i.e., extracted query parameter values, will be considered.

In summary, the command fetches a webpage, performs an XPath extraction on the links (<a> tags) present in it, and captures the query parameter value for links that include a non-empty "q" parameter.