Scans a disk image for regular expressions and other content.
bulk_extractor -o output_dir [options] [ image | -R dir ]
bulk_extractor scans a disk image (or any other file) for a large num‐
ber of pre-defined regular expressions and other kinds of content.
These items are called features. When it finds a feature, bulk_extrac‐
tor writes the output to an output file. Each line of the output file
contains a byte offset at which the feature was found, a tab, and the
actual feature. Features therefore cannot contain the end-of-line char‐
bulk_extractor includes native support for EnCase (.E01) and AFFLIB
(.aff) files, if it compiled and linked on a system containing those
libraries. Alternatively, the -R option can be used to recursively scan
and process a directory of individual files (disk images in such a di‐
rectory will be treated as files, not as disk images).
bulk_extractor is multi-threaded. By specifying the -j option, multiple
copies of the program can be run. Each thread writes its results into
its own feature file. The files are then combined by the primary thread
when all of the secondary threads complete.
bulk_extractor is a two-phase program. In phase 1 the features are ex‐
tracted. In phase 2 a histogram is created of relevant features.
bulk_extractor will also create a wordlist of all the words that are
found in the disk image. This can be used as a dictionary for cracking
The options are as follows:
Specifies the output directory, which will be created by
bulk_extractor if necessary. If the output directory contains
data from a partial bulk_extractor run, bulk_extractor will at‐
tempt to resume where the previous run left off.
Read the contents of bannerfile.txt and stamp it at the begin‐
ning of each output file. This might be useful if you have some
kind of privacy banner that needs to be stamped at the top of
all of your files.
Specifies an alert list, (or red list), which is a list of terms
that, if found, will be specifically flagged in a special alert
file that begins with the letters ALERT. The alert list may
contain individual terms, which must be found in their entirity
and are case-sensitive, or wildcards with standard Unix globbing
(e.g. *@company.com). Globbed terms are case-insensitive.
Specifies a stop list, (or white list), which is a list of terms
that, if found, will be placed in a special stopped file (rather
than in the main file). The whitelist may also contain globbed
Specify random sampling parameters.
Open a disk image and print the information found at path. The
format specification may be r for raw output and h for hex out‐
Specify -p - for interactive mode.
Specify -p -http for HTTP mode.
These commands are useful for tuning operation:
-C NN Specifies the size of the context window.
The following commands are useful for debugging:
-V Print the version number
Restarts the program from where it left off for a particular di‐
-B nn Set the dedup Bloom filter to nn bits. This is used by the
-M nn Specifies a maximum recursion depth of nn.
Start on page number pagenum.
Finally, you can control scanners with these options: -P
bulk_extractor is based on a feature extractor and named entity recog‐ nizer developed for SBook in 1991. The feature extractor was repurposed for disk images in 2003. The stand-alone bulk_extractor program was rewritten in 2005 and publicly released in 2007. The multi-threaded bulk_extractor was released in May 2010.