Dr. Andrew Broad
Computer Science
Java
Extracting Text from a Binary File

BinText is a simple Java program for extracting ASCII text from an arbitrary binary file, ignoring control codes. This can be useful for salvaging textual data from a file which no application-program can read, or if a file becomes corrupted and the application can no longer read it.

BinText has a simple command-line interface: its usage is as follows:

java BinText file (start_offset (stop_offset (line_length)))

The offsets refer to the range of positions in the file from which you want to extract text (from 0 to one less than the length of the file in bytes). If you don't specify the offsets, it will process the whole file. If you want to specify line_length but not stop_offset, type a negative value such as -1 for stop_offset.

Specifying a line-length causes newlines to be inserted at the end of each line (no word-wrap). For example, to extract text from a file X.BIN with a line-length of 40, you'd use the following command-line:

java BinText X.BIN 0 -1 40

BinText accepts the following command-line flags:

• -m: Treat the MSB of each byte as 0 (sometimes text is stored using MSBs as special markers, which are meant to be interpreted as ASCII codes 32-127 rather than 160-255).
• -o: Offset ASCII codes 0-31 by 32 (i.e. treat them as ASCII codes 32-63). By default, BinText treats these codes as spaces (32).
• -a: Print the ASCII codes numerically (separated by commas) rather than printing characters. This is useful if you suspect that a file contains all 0s, for example, or if you want to see how newlines are encoded (10: line-feed, 13: carriage-return). This option ignores line_length, -m and -o.