More fine grained highlighting

[piotr-dobrogost]

It would be nice to be able to specify more fine-grained highlighting like this:

    "highlights": {
      "session": {
        "pattern": "(?<session>Session) (?<session_id>[a-zA-Z0-9]*) (?<created>created))",
        "colors":{
          "session": "gold1",
          "session_id": "aqua",
          "created": "white"
        }
      }
    }

[tstack]

I think fine-grained styling for the captures sounds reasonable... maybe not this exact approach, but something.

I just wish you had mentioned it earlier, I was going to release v0.14.0 today... 😉

[tstack]

I've pushed a change that should allow you to style the captures. Here's an example from the test dir:

lnav/test/formats/partitions/format.json

Lines 5 to 19 in a20955d

	"body": {
	"highlights": {
	"req": {
	"pattern": "DHCPREQUEST on (?<device>[^ ]+) to (?<ip>[^ ]+) port (?<port>[^ ]+)",
	"base-style": {
	"background-color": "green"
	},
	"captures": {
	"device": {
	"color": "blue"
	}
	}
	}
	}
	}

[piotr-dobrogost]

Is this supposed to work also in the generic highlights section (This object contains the definitions for patterns to be highlighted in a log message.)?
I'm asking because it's not mentioned in the docs at https://docs.lnav.org/en/latest/formats.html in the description of the generic highlights section and does not seem to work:

    "highlights": {
      "session_read_updated": {
        "pattern": "Session (?<session_id>[a-zA-Z0-9]*) (?<session_action>read|updated)",
        "base-style": {
          "color": "white"
        },
        "captures": {
          "session_id": {
            "color": "aqua"
          },
          "session_action": {
            "underline": true
          }
        }
      }
    },

Notice how session id does not have aqua color and the word "updated" is not underlined. Also where does the color of the word "updated" come from?

Is the base-style required and if not what's the default style being used?

[tstack]

Is this supposed to work also in the generic highlights section

No, that section existed before v0.14, so I didn't want to break it. The new functionality is in the "value" section. But, I think you can add highlights to the "body" value to have the same effect.

Pass -W to have lnav print out configuration warnings. I think it would complain about not understanding base-style.

[piotr-dobrogost]

Is this supposed to work also in the generic highlights section

No, that section existed before v0.14, so I didn't want to break it. The new functionality is in the "value" section. But, I think you can add highlights to the "body" value to have the same effect.

Thanks, will try it.
It seems supporting this here would be backward-compatible – see below.

Pass -W to have lnav print out configuration warnings. I think it would complain about not understanding base-style.

Not really. It does complain about all colors, though:

(…)
⚠ warning: unexpected value for property “/ian_log/value/status/highlights/error/color”
 --> /home/piotr/.config/lnav/formats/installed/ian_log.json:149
 |             "color": "red"              
 =   help: Available Properties
           pattern <regex>
           base-style/ 
           captures/
⚠ warning: unexpected value for property “/ian_log/highlights/session_read_updated/base-style/color”
 --> /home/piotr/.config/lnav/formats/installed/ian_log.json:178
 |           "color": "white"              
 =   help: Available Properties
           pattern <regex>
           color #<hex>|<name>
           background-color #<hex>|<name>
           underline <enabled>
           blink <enabled>
           nestable <enabled>
(…)

and about underline:

⚠ warning: unexpected value for property “/ian_log/highlights/session_read_updated/captures/session_action/underline”
 --> /home/piotr/.config/lnav/formats/installed/ian_log.json:185
 |             "underline": true           
 =   help: Available Properties
           pattern <regex>
           color #<hex>|<name>
           background-color #<hex>|<name>
           underline <enabled>
           blink <enabled>
           nestable <enabled>

[piotr-dobrogost]

Is this supposed to work also in the generic highlights section

No, that section existed before v0.14, so I didn't want to break it. The new functionality is in the "value" section. But, I think you can add highlights to the "body" value to have the same effect.

It does not seem to work (no coloring is being done):

    "value": {
      "body": {
        "highlights": {
          "session_read_updated": {
            "pattern": "Session (?<session_id>[a-zA-Z0-9]*) (?<session_action>read|updated)",
            "base-style": {
              "color": "white"
            },
            "captures": {
              "session_id": {
                "color": "aqua"
              },
              "session_action": {
                "underline": true
              }
            }
          }
        }
      },

Message:

[2026-01-07 13:05:42.021652+01:00 req_id:0nqfdYEadp9D5Bzwzx9ZpxFBJ req:post@api/login/init ua_id:QIqcJCzvmQdQNMSYomNatHdpZ1WBky3 sess:I000bdq1fXH35aTC45OiJa4FwMz user:- ip:127.0.0.1 pid:1 thr:7f502a4a8040 busy:1 level:DEBUG src:1370@sfx.util.session]
 Session I000bdq1fXH35aTC45OiJa4FwMz updated (0.000 sec, 0.05 kB) with data:
 {'flow.login-36oK80PClYJ87LD7IRUdcScLu.memo': {}}

Binary downloaded from https://github.com/tstack/lnav/actions/runs/24174703981/artifacts/6343284827 listed at https://github.com/tstack/lnav/actions/runs/24174703981/job/70553542626
Btw, is there any stable link to the latest binary?

[tstack]

Ah, sorry, I don't think I'm going to be able to get the highlighting working for multi-line bodies in this first version. I'd like to get a release out in the next day or two.