.. _command-line:

**********************************
Running YARA from the command-line
**********************************

In order to invoke YARA you’ll need two things: a file with the rules you want
to use and the target to be scanned. The target can be a file, a folder, or a
process. ::

  yara [OPTIONS] RULES_FILE TARGET

In YARA 3.8 and below ``RULES_FILE`` was allowed to be a file with rules in source
form or in compiled form indistinctly. In YARA 3.9 you need to explicitly specify
that ``RULES_FILE`` contains compiled rules by using the -C flag. ::

  yara [OPTIONS] -C RULES_FILE TARGET

This is a security measure to prevent users from inadvertently using compiled
rules coming from a third-party. Using compiled rules from untrusted sources can
lead to the execution of malicious code in your computer.

For compiling rules beforehand you can use the ``yarac`` tool. This way can save
time, because for YARA it is faster to load compiled rules than compiling the
same rules over and over again.

You can also pass multiple source files to `yara` like in the following example::

  yara [OPTIONS] RULES_FILE_1 RULES_FILE_2 RULES_FILE_3 TARGET

Notice however that this only works for rules in source form. When invoking YARA
with compiled rules a single file is accepted.

In the example above all rules share the same "default" namespace, which means
that rule identifiers must be unique among all files. However you can specify a
namespace for individual files. For example ::

  yara [OPTIONS] namespace1:RULES_FILE_1 RULES_FILE_2 RULES_FILE_3 TARGET

In this case ``RULE_FILE_1`` uses ``namespace1`` while ``RULES_FILE_2`` and
``RULES_FILE_3`` share the default namespace.

In all cases rules will be applied to the target specified as the last argument
to YARA, if it’s a path to a directory all the files contained in it will be
scanned. By default YARA does not attempt to scan directories recursively, but
you can use the ``-r`` option for that.

Available options are:

.. program:: yara

.. option:: -C --compiled-rules

  RULES_FILE contains rules already compiled with yarac.

.. option:: -c --count

  Print only number of matches.

.. option:: -d <identifier>=<value> --define=identifier=value

  Define external variable. This option can be used multiple times.

.. option:: --fail-on-warnings

  Treat warnings as errors. Has no effect if used with --no-warnings.

.. option:: -f --fast-scan

  Fast matching mode.

.. option:: -h --help

  Show help.

.. option:: -i <identifier> --identifier=<identifier>

  Print rules named <identifier> and ignore the rest.

.. option:: --max-process-memory-chunk=<size>

  When scanning process memory read the data in chunks of the given size.

.. option:: -l <number> --max-rules=<number>

  Abort scanning after matching a number of rules.

.. option:: --max-strings-per-rule=<number>

  Set maximum number of strings per rule (default=10000). If a rule has more
  then the specified number of strings an error will occur.

  .. versionadded:: 3.7.0

.. option:: -x <module>=<file> --module-data=<module>=<file>

  Pass the content of <file> as data to <module>. Example: -x cuckoo=/cuckoo_report.json.

.. option:: -n --negate

  Print not satisfied rules only (negate).

.. option:: -N --no-follow-symlinks

  Do not follow symlinks when scanning.

.. option:: -w --no-warnings

  Disable warnings.

.. option:: -m --print-meta

  Print metadata.

.. option:: -D --print-module-data

  Print module data.

.. option:: -e --print-namespace

  Print rules' namespace.

.. option:: -S --print-stats

  Print rules' statistics.

.. option:: -s --print-strings

  Print matching strings.

.. option:: -L --print-string-length

  Print length of matching strings.

.. option:: -g --print-tags

  Print tags.

.. option:: -r --recursive

  Recursively search for directories. It follows symlinks.

.. option:: --scan-list

  Scan files listed in FILE, one per line.

.. option:: -z <size> --skip-larger=<size>

  Skip files larger than the given <size> in bytes when scanning a directory.

  .. versionadded:: 4.2.0

.. option:: -k <slots> --stack-size=<slots>

  Allocate a stack size of "slots" number of slots. Default: 16384. This
  will allow you to use larger rules, albeit with more memory overhead.

  .. versionadded:: 3.5.0

.. option:: -t <tag> --tag=<tag>

  Print rules tagged as <tag> and ignore the rest.

.. option:: -p <number> --threads=<number>

  Use the specified <number> of threads to scan a directory.

.. option:: -a <seconds> --timeout=<seconds>

  Abort scanning after a number of seconds has elapsed.

.. option:: -v --version

  Show version information.


Here you have some examples:

* Apply rule in */foo/bar/rules* to all files in the current directory.
  Subdirectories are not scanned::

    yara /foo/bar/rules  .

* Apply rules in */foo/bar/rules* to *bazfile*. Only reports rules tagged as
  *Packer* or *Compiler*::

    yara -t Packer -t Compiler /foo/bar/rules bazfile

* Scan all files in the */foo* directory and its subdirectories::

    yara /foo/bar/rules -r /foo

* Defines three external variables *mybool*, *myint* and *mystring*::

    yara -d mybool=true -d myint=5 -d mystring="my string" /foo/bar/rules bazfile

* Apply rules in */foo/bar/rules* to *bazfile* while passing the content of
  *cuckoo_json_report* to the cuckoo module::

    yara -x cuckoo=cuckoo_json_report /foo/bar/rules bazfile
