cover (1) - Linux Manuals

cover: report coverage statistics


cover - report coverage statistics


version 1.03


 cover -help -info -version
       -summary -report report_format -outputdir dir
       -select filename -ignore filename
       -select_re RE -ignore_re RE
       -write [db] -delete -dump_db -launch
       -coverage criterion
       -test -gcov
       -make [make]
       -add_uncoverable_point -delete_uncoverable_point
       -clean_uncoverable_points -uncoverable_file
       [report specific options]
       coverage_database [coverage_database ...]


Report coverage statistics in a variety of formats.

The summary option produces a short textual summary. Other reports are available by using the report option.

The following reports are currently available:

 text                  - detailed textual summary
 html                  - detailed HTML reports
 html_basic            - detailed HTML reports with syntax highlighting
 compilation           - output in a format similar to Perl


The following command line options are supported:

 -h -help              - show help
 -i -info              - show documentation
 -v -version           - show version

 -silent               - don't print informational messages (default off)
 -summary              - give summary report                (default on)
 -report report_format - report format                      (default html)
 -outputdir            - directory for output               (default db)
 -launch               - launch report in viewer (if avail) (default off)

 -select filename      - only report on the file            (default all)
 -ignore filename      - don't report on the file           (default none)
 -select_re RE         - append to REs of files to select   (default none)
 -ignore_re RE         - append to REs of files to ignore   (default none)
 -write [db]           - write the merged database          (default off)
 -delete               - drop database(s)                   (default off)
 -dump_db              - dump database(s) (for debugging)   (default off)

 -coverage criterion   - report on criterion  (default all available)

 -test                 - drop database(s) and run make test (default off)
 -gcov                 - run gcov to cover XS code     (default on if using gcc)
 -make make_prog       - use the given 'make' program for 'make test'

 other options specific to the report format


Tool accepts -report option:
html|html_minimal (default)
HTML reporting. Percentage thresholds are color-coded and configurable via -report_c0 <integer>, -report_c1 <integer> and -report_c2 <integer>.:

    0%      75%      90%      100%
    |   ..   |   ..   |   ..   |
       <c0      <c1      <c2   c3
       red     yellow   orange green
HTML reporting with syntax highlighting if PPI::HTML or Perl::Tidy module is detected. Like html|html_minimal reporting, percentage thresholds are color-coded and configurable.
Plain text reporting.
Like text but hacked to give a minimal output in a format similar to that output by Perl itself so that it's easier to step through the untested locations with Emacs compilation mode.


Any number of coverage databases may be specified on the command line. These databases will be merged and the reports will be based on the merged information. If no databases are specified the default database (cover_db) will be used.

The -write option will write out the merged database. If no name is given for the new database, the first database read in will be overwritten. When this option is used no reports are generated by default.

Specify -select and -ignore options to report on specific files.

Specify -coverage options to report on specific criteria. By default all available information on all criteria in all files will be reported. Available coverage options are statement, branch, condition, subroutine, and pod. However, if you know you only want coverage information for certain criteria it is better to only collect data for those criteria in the first place by specifying them at that point. This will make the data collection and reporting processes faster and less memory intensive. See the documentation for Devel::Cover for more information.

The -test option will delete the databases and run your tests to generate new coverage data before reporting on it. Devel::Cover knows how to work with standard Perl Makefiles as well as Module::Build based distributions. For detailed instructions see the documentation for ExtUtils::MakeMaker at <> or for Module::Build at <> both of which come as standard in recent Perl distributions.

The -gcov option will try to run gcov on any XS code. This requires that you are using gcc of course. If you are using the -test option will be turned on by default.


The following exit values are returned:

0 All operations were completed successfully.

>0 An error occurred.

With the -test option the exit status of the underlying test run is retuened.


Did I mention that this is alpha code?

See the BUGS file.


Copyright 2001-2013, Paul Johnson (paul [at]

This software is free. It is licensed under the same terms as Perl itself.

The latest version of this software should be available from my homepage: