Find Positions of a Hexadecimal Sequence in a File

This page answers questions like these:

Detect Whether A File Contains A Hexadecimal String:

grep -P '\xNN\xNN\xNN...' FILE

In some versions of Unix/Linux, you can use Perl regular expressions to grep hex strings.
e.g. “grep -P '\x48\x65\x6c\x6c\x6f' FILE” will grep for "Hello".
Pros: Faster than the methods presented below.
Cons: For binary files, it only tells you whether the file contains the string or not. (For text files, it shows you the matching lines just like normal grep.)

Find the positions of hexadecimal string HEXSTRING in file FILE. Positions are listed in order and on separate lines. Position zero is the first character of the file.
N.B. HEXSTRING must have each byte’s hex separated by one space, e.g. "Hello" would be represented by "48 65 6c 6c 6f" or "48 65 6C 6C 6F".
Pros: Handles both text and binary files. Handles any byte value from 00 to ff. Handles both uppercase and lowercase hexadecimal. Can use regular expression matching instead of a plain hex string.
Cons: Very slow. Some systems don’t have the -o option to grep. Doesn’t handle overlapping hex strings or patterns.

Find the positions of lowercase hexadecimal string HEXSTRING in file FILE. Positions are listed in order and on separate lines. Position zero is the first character of the file.
N.B. HEXSTRING must have each byte’s hex separated by one space, e.g. "Hello" would be represented by "48 65 6c 6c 6f".
Pros: Handles both text and binary files. Handles any byte value from 00 to ff. Can use regular expression matching instead of a plain hex string. Doesn’t rely on the -o option to grep.
Cons: Extremely slow. Doesn’t handle overlapping hex strings or patterns.

file-find-hexadecimal.txt
Linux-Unix/find-positions-of-hexadecimal-sequence-in-file.htm
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