More jq from journalctl

I've found another use case for `jq` when parsing service logs stored with `journald`. This time, I want to extract all non-INFO level logs from the service called slinky. In the previous example, I used `awk` to print only the part of a line that is valid JSON. However, `sed` might be better suited for this task. The following rule removes (replaces with an empty string) the beginning of the line up to the colon followed by a space ": ", which separates the timestamp from the log entry (JSON):

's/^.\+\]:\ //'

Examples

There are two examples of the command pipelines below. 

The first one checks the logs from the last 2 hours:

journalctl --since "2 hours ago" -u slinky.service\
 | sed -e 's/^.\+\]:\ //'\
 | jq 'select(.level != "info") '

The second one continuously prints new entries:

journalctl -f -u slinky.service\
 | stdbuf -oL sed -e 's/^.\+\]:\ //'\
 | jq 'select(.level != "info") '

The `journalctl` command is nearly identical in both examples (`--since` vs. `-f`). The `jq` select statement and the `sed` string replacement are the same. The main difference is that the latter uses the `stdbuf` command. It allows running the following command with modified buffering. The `-oL` option means that the standard output of the `sed` command is flushed line by line, enabling each entry to be passed immediately to `jq`.

Download GitHub Actions logs

I've been using GitHub CLI more and more lately. Recently, I had to debug a failing of GitHub Action run. Browsing long logs in the WebUI is a bit clunky, so I started downloading the full logs via the CLI. 

It is straightforward `gh` command if you already know the run number --  and that information can be obtained from the `gh` command with different options. 

I end up with following two-part shell snippet: 

VIEW=$(\
 gh run list \
 | grep $(git branch --show-current) \
 | head -1\
 | awk '{print $(NF-2)}') \
&& \
gh run view ${VIEW} --log > ~/Downloads/${VIEW}.log
 

The first command assign the run number to the VIEW variable. It parses the output of the `gh run list` command by:

• filtering run for the current git branch (`grep`)
• taking the most recent one (`head`)
• extracting the run number (third column from the end via `awk`).

The VIEW variable is then used to fetch the logs for the specific run and save them to the uniquely named file in the Downloads folder.

Assumptions:

• the workflow run belongs to the current git branch
• it's the latest run for the branch 
• The Downloads folder doesn't already contain a file with the same number (it would be overwritten)