[new feature request] shellcheck summary with stats

[weakcamel]

For new checks and feature suggestions

• [x] https://www.shellcheck.net/ (i.e. the latest commit) currently gives no useful warnings about this (not applicable)
• [x] I searched through https://github.com/koalaman/shellcheck/issues and didn't find anything related

I believe it would be interesting to see a very simple summary of findings by shellcheck

• to be able to "roughly" assess the quality, provide a report etc.
• potentially, to be able to extract the number of findings and e.g. fail the CI build if number of findings has increased

Here's a snippet or screenshot that shows the problem:

#!/bin/bash

FOO=test.sh

ls $0

Here's what shellcheck currently says:

$ shellcheck test.sh

In test.sh line 3:
FOO=test.sh
^-^ SC2034: FOO appears unused. Verify use (or export if used externally).


In test.sh line 5:
ls $0
   ^-- SC2086: Double quote to prevent globbing and word splitting.

Did you mean:
ls "$0"

For more information:
  https://www.shellcheck.net/wiki/SC2034 -- FOO appears unused. Verify use (o...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...

Here's what I wanted or expected to see:

$ shellcheck test.sh

In test.sh line 3:
FOO=test.sh
^-^ SC2034: FOO appears unused. Verify use (or export if used externally).


In test.sh line 5:
ls $0
   ^-- SC2086: Double quote to prevent globbing and word splitting.

Did you mean:
ls "$0"

For more information:
  https://www.shellcheck.net/wiki/SC2034 -- FOO appears unused. Verify use (o...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...

Summary of findings:
  error: 0
  warning: 1
  info: 1
  style: 0
  TOTAL: 2

[tedmiston]

This would be awesome to have! I've been spoiled by other popular linters...

Here is my temporary hack of a bash function in the meantime:

function shellcheck-summary {
  # `script` here works like `tee` but preserves colored output
  # - https://stackoverflow.com/a/3515296/149428
  script -q out.txt ./lint.sh

  errors=$(grep -o '(error)' out.txt | wc -l | xargs)
  warns=$(grep -o '(warning)' out.txt | wc -l | xargs)
  infos=$(grep -o '(info)' out.txt | wc -l | xargs)
  styles=$(grep -o '(style)' out.txt | wc -l | xargs)
  
  echo -e "\nshellcheck summary\n"
  echo "- error:   ${errors}"
  echo "- warning: ${warns}"
  echo "- info:    ${infos}"
  echo "- style:   ${styles}"

  rm out.txt
}

(lint.sh is a script that runs my shellcheck command and some other stuff, but you could probably just put the shellcheck command in here directly as an alternative)