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LICENSECHECK(1p) User Contributed Perl Documentation LICENSECHECK(1p)


licensecheck - simple license checker for source files


Version v3.3.5


    licensecheck [ --help | --version ]
    licensecheck [ --list-licenses | --list-naming-schemes ]
    licensecheck [OPTION...] PATH [PATH...]


licensecheck attempts to determine the license that applies to each file passed to it, by searching the start of the file for text belonging to various licenses.

If any of the arguments passed are directories, licensecheck will add the files contained within to the list of files to process.

When multiple PATHs are provided, only files matching --check and not --ignore are checked.


Resolving patterns

Since v3.2.

comma-separated priority list of license naming schemes to use for license identifiers (default value: unset (use verbose description))

Since v3.2.

list identifiers for all detectable licenses and exit

Since v3.2.

list all available license naming schemes and exit

Selecting files

Since v2.10.10.

regular expression of files to include when more than one PATH is provided (default value: common source files)

Since v2.10.10.

regular expression of files to skip when more than one PATH is provided (default value: some backup and VCS files)

Since v2.10.7.

traverse directories recursively

Parsing contents

Since v2.10.3.

number of lines to parse from top of each file; implies optimistic search including only first cluster of detected copyrights or licenses; set to 0 to parse the whole file (and ignore --tail) (default value: 60)

Since v2.15.10.

number of bytes to parse from bottom of each file when parsing only from top of each file and finding nothing there; set to 0 to avoid parsing from end of file (or set --lines to 0 and ignore this setting) (default value: 5000 (roughly 60 lines))

Since v2.15.10.

try decode source files from the specified codec, with "iso-8859-1" as fallback (default value: unset (no decoding))

Reporting results

Since v2.10.7.

add copyright statements to license information

Since v3.3.0.

Log files in PATHs matching neither --check nor --ignore as warnings (default: log as debug)

Since v2.12.2.

print license information as "TAB"-separated fields, for processing with line-oriented tools like "awk" and "sort"

Since v3.0.0.

print license information like a Debian copyright file; implies --copyright and --shortname-scheme=debian,spdx

Since v3.0.18.

printf-string used between multiple plain list items in Debian copyright file (default value: '\n ' (NEWLINE SPACE))

Since v3.0.18.

printf-string used between multiple RFC822-style items in Debian copyright file (default value: '\n  ' (NEWLINE SPACE SPACE))

Since v3.0.19.

printf-string used between years and owners in Debian copyright file (default value: ', ' (COMMA SPACE))

Since v3.0.0.

merge same-licensed files in Debian copyright file


print help message and exit
print version and copyright information and exit
Since v3.3.0.

Emit only error messages to STDERR (with option --quiet), or (in addition errors and warnings) also notices/debug/traces. The more "noisy" option wins if several are set. (default: emit errors and warnings


If defined, will disable color. Consulted before COLOR.
Can be set to 0 to explicitly disable colors. The default is to use color when connected to a terminal.
Used to emit varying details about discoveries to STDERR when verbosity is not set using either of options --quiet, --verbose, --debug or --trace. See Log::Any::Adapter::Screen for more details.
The default formatter groks these variables. See formatter in Log::Any::Adapter::Screen for more details.


The exact output may change between releases, due to the inherently fragile scanning of unstructured data, and the ongoing improvements to detection patterns. For some level of stability, use one of the machine-readable output formats and define a --shortname-scheme.

Option --deb-fmt was deprecated since v3.2. Please use option --shortname-scheme=debian,spdx instead.


Other similar tools exist.

Here is a list of known tools also command-line based and general-purpose:

Written in Perl.>
Written in Python.

Specific to Debian packages.>
Written in Python.>
Written in Ruby.>
Written in Ruby.>
Written in C++.

Used in FOSSology <> (along with Monk and Nomos apparently unavailable as standalone command-line tools).>
Written in Go.>
Written in Python.


Jonas Smedegaard "<>"


This program is based on the script "licensecheck" from the KDE SDK, originally introduced by Stefan Westerfeld "<>".

  Copyright © 2007, 2008 Adam D. Barratt
  Copyright © 2012 Francesco Poli
  Copyright © 2016-2022 Jonas Smedegaard
  Copyright © 2017-2022 Purism SPC

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License along with this program. If not, see <>.

2023-01-15 perl v5.36.0