Grep Binary Files – Resolve ‘Binary File (standard input) Matches’ Error

If there is a NUL character anywhere in the file, grep will consider it as a binary file.

There might a workaround like this cat file | tr -d '\000' | yourgrep to eliminate all null first, and then to search through file.

Looking at the grep manual, this seems to be because (bold mine):

If type is ‘without-match’, when grep discovers null input binary data it assumes that the rest of the file does not match; this is equivalent to the -I option.

However, grep also considers other data as indicating binary files:

Non-text bytes indicate binary data; these are either output bytes that are improperly encoded for the current locale (see Environment Variables), or null input bytes when the -z (--null-data) option is not given (see Other Options).

So the message won't be printed if:

• the -I/--binary-files=without-match options are given
• and the binary-ness is due to null bytes.

However, that's not the case with the example input. The example file is treated as binary because it doesn't fit the current locale (probably some UTF locale), not because it has null bytes. Otherwise:

% LC_ALL=C grep 8 test-file  
x���J�@`�y��
dIf��(��P������6u G7}S��8�0�&���'����9&�lL�Çl�t�y,蒩AU����F��cT�~
                                                                 �ʱ�k��]�Yx�$}�/����O�O�ù�4�����X��zd�Ȉ��W���,�2<�/�d�����+L
                                                                                                                            �Y�����7��PB

If I add a null byte to the file, grep fails successfully:

% printf '\0' >> test-file
% grep -I 8 test-file    
% echo $?
1