Command line switches

Most configuration options are also available as command line switches, so that you can e.g. only run certain checks at a time to focus attention on those issues.

Common use cases

Here are a couple of common use case and their respective command line switches:

Output Formats

Use --format to format the output in one of the following formats:

• --format flycheck for Flycheck output
• --format json for JSON output

Only run some checks

To run only a subset of checks, you can use the --checks or the -c alias (also aliased as --only).

# to only run the Readability checks, use:

$ mix credo --only readability

# to only run Readability checks and Warnings, use:

$ mix credo --only readability,warning

The second example illustrates how the command takes a comma-separated list. All commands matching any of the passed items will be run.

You can use partial names to quickly run checks. mix credo --only todo will show all # TODO comments since todo will match Credo.Check.Design.TagTODO. mix credo --only inspect will show you all calls to IO.inspect since it matches Credo.Check.Warning.IoInspect.

Ignore some checks

To ignore selected checks, you can use the --ignore-checks or the -i alias (also aliased as --ignore).

# to ignore all Readability checks, use:

$ mix credo --ignore readability

# to ignore all Readability checks and the DuplicatedCode check, use:

$ mix credo --ignore readability,duplicated

The second example illustrates how the command takes a comma-separated list. All commands matching any of the passed items will be ignored.

You can use partial names to quickly exclude checks. mix credo --ignore nameredec will exclude all checks for variables/parameters having the same name as declared functions by matching Credo.Check.Warning.NameRedeclarationBy...

Re-enable disabled checks

Use --enable-disabled-checks [pattern] to re-enable checks that were disabled in the config using {CheckModule, false}. This comes in handy when using checks on a case-by-case basis

As with other check-related switches, pattern is a comma-delimted list of patterns:

$ mix credo info --enable-disabled-checks Credo.Check.Readability.Specs,Credo.Check.Refactor.DoubleBooleanNegation

Of course, we can have the same effect by choosing the pattern less explicitly:

$ mix credo info --enable-disabled-checks specs,double

Parsing source from STDIN

You can also use Credo to parse source that has been piped directly into it. This is especially useful when integrating with external editors. You can use this feature by passing the --read-from-stdin option as follows:

$ echo 'IO.puts("hello world");' | mix credo --format flycheck --read-from-stdin
# stdin:1: C: There is no whitespace around parentheses/brackets most of the time, but here there is.

Notice the origin if the source is coming annotated as stdin, you can change this annotation by passing it along after option like so:

$ echo 'IO.puts("hello world");' | mix credo --format flycheck --read-from-stdin /path/representing/the_current/source.ex
# /path/representing/the_current/source.ex:1: C: There is no whitespace around parentheses/brackets most of the time, but here there is.

Do note with the passed option as filename is a stub that is just used to prefix the error and so certain editors can annotate the original file.

Show all issues (including low priority ones)

By default, Credo's CLI output shows only the 5 most important issues per category. Using --all, you can show all the important issues in each category.

Use the --all-priorities switch to include low priority issues in the output (aliased as --strict).

Command line switches and config file

Most configuration options are also available as command line switches.

➜ mix credo suggest --help
Usage: mix credo suggest [paths] [options]

Suggests objects from every category that Credo thinks can be improved.

Example: $ mix credo suggest lib/**/*.ex --only consistency --format json

Arrows (↑ ↗ → ↘ ↓) hint at the importance of an issue.

Suggest options:
  -a, --all                     Show all issues
  -A, --all-priorities          Show all issues including low priority ones
  -c, --checks                  Only include checks that match the given strings
      --checks-with-tag         Only include checks that match the given tag (can be used multiple times)
      --checks-without-tag      Ignore checks that match the given tag (can be used multiple times)
      --config-file             Use the given config file
  -C, --config-name             Use the given config instead of "default"
      --enable-disabled-checks  Re-enable disabled checks that match the given strings
      --files-included          Only include these files (accepts globs, can be used multiple times)
      --files-excluded          Exclude these files (accepts globs, can be used multiple times)
      --format                  Display the list in a specific format (json,flycheck,oneline)
  -i, --ignore-checks           Ignore checks that match the given strings
      --ignore                  Alias for --ignore-checks
      --min-priority            Minimum priority to show issues (high,medium,normal,low,lower or number)
      --mute-exit-status        Exit with status zero even if there are issues
      --only                    Alias for --checks
      --strict                  Alias for --all-priorities

General options:
      --[no-]color              Toggle colored output
  -v, --version                 Show version
  -h, --help                    Show this help

Some of these are not available as configuration options in .credo.exs:

• --enable-disabled-checks [PATTERN] activates disabled checks on the fly
• --mute-exit-status forces Credo to exit with an exit status of 0