Shellcheck optionals

[06kellyjac]

Added the ability to use optional shellcheck checks.

Testing Script:

#!/usr/bin/env bash

yo="a"
[ -z "$yo" ]

which ls

Testing pre-commit config:

---
repos:
  - repo: local
    hooks:
      - id: shellcheck
        name: Shellcheck Bash Linter
        description: Performs linting on bash scripts
        entry: ../pre-commit/hooks/shellcheck.sh
        language: script
        # args: ["--enable require-variable-braces,deprecate-which"] # comment and uncomment

---

logging the command that would be ran, forcing exit 1 to show the logs:

With:

pre-commit run -a
Shellcheck Bash Linter...................................................Failed
- hook id: shellcheck
- exit code: 1

shellcheck --enable="require-variable-braces,deprecate-which" "sample.sh"

In sample.sh line 4:
[ -z "$yo" ]
      ^-^ SC2250: Prefer putting braces around variable references even when not strictly required.
...
...

Without:

pre-commit run -a
Shellcheck Bash Linter...................................................Failed
- hook id: shellcheck
- exit code: 1

shellcheck "sample.sh"

--enable will only be ran if it's provided in the pre-commit config. This is to avoid issues with shellcheck before 0.7.0 when --enable was added

[yorinasub17]

Thanks for your contribution and apologies for the delay in reviewing this! This feature makes sense and this looks like a good start, but have some suggestions for improvements.

[06kellyjac]

I've updated the regex used for the shebang & file ending as shellcheck should match the following shells:

• sh
• ash
• dash
• bash
• bats
• ksh
  src

---

Shebang regex:
Was: '^#!.*sh'
Now: '^#!\(/\|/.*/\|/.* \)\(\(ba\|da\|k\|a\)*sh\|bats\)$'

Test cases:
https://pastebin.com/BKB92wx2

Previous regex matched a lot of invalid shebangs & missed the 6 valid bats shebangs.

Current regex matches just the 6 correct shebangs from each valid shell.
There are probably some cases that I can't think of but it's a lot safer than the existing one.
A compromise would be something like: '^#!/.*\(\(ba\|da\|k\|a\)*sh\|bats\)$'
It matches the zsh fish and extra characters + valid shell ones but they're all at least valid.

---

File ending regex:
Was: \.sh$|bash$
Now: .+\.(sh|bash|dash|ksh|ash|bats)$

Test cases:
https://pastebin.com/JRJg8N13

Testing script:

#!/usr/bin/env bash
test() {
	if [[ "$1" =~ .+\.(sh|bash|dash|ksh|ash|bats)$ ]]; then
		echo "match     - $1"
	else
		echo "not match - $1"
	fi
}

while IFS= read -r FILE; do
	if [[ "$FILE" != "" ]]; then
		test "$FILE"
	fi
done <<EOF
TEST CASES HERE
EOF

Previous regex would match .sh bash and miss file.ksh file.dash file.ash file.bats

Current regex only matches the 3 normal file names + also matches just .sh .bash etc, which are very unusual but valid file names.
There's no extra checking for slashes etc because file names & escapes could confuse things, just the extension should be enough.

[yorinasub17]

Apologies for the delay in getting back to you on this! I have a few style nits (tabbing should be 2 spaces, and the while loop should use $# -gt 0), but since they're minor will apply them in a separate PR after merging.

[06kellyjac]

No problem

tabbing should be 2 spaces
Ahh. I think the original changes had 2 spaces. I think I ran shfmt at some point or something

the while loop should use $# -gt 0
The google style guide says it's fine to use (( )) in the testing strings section, and focuses on (( )) in the arithmetic section. But it's up to you :)

[yorinasub17]

The google style guide says it's fine to use (( )) in the testing strings section, and focuses on (( )) in the arithmetic section. But it's up to you :)

shellcheck actually flags this because $# is a number, not a string, so you need to use -gt not >.

[06kellyjac]

SC2071 only complains about the use of > and < within [[ ]]

(( )) can only handle numbers and shellcheck has no issues

Using -gt doesn't work with (( )) and causes the following shellcheck issues

[yorinasub17]

Ahhh I think you are right. Apologies for that! I was so used to switching to [[]] everywhere I think I missed the first pass of shellcheck.

[06kellyjac]

no problem 😃
I'll pop in a PR swapping back to spaces soon ah you've got one already, nice