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The manpage for grep describes the -I flag as follows:

-I Ignore binary files. This option is equivalent to --binary-file=without-match option.

It also says this about binary files:

--binary-files=value Controls searching and printing of binary files. Options are binary, the default: search binary files but do not print them; without-match: do not search binary files; and text: treat all files as text.

I cannot think of a scenario where I would care about matches in binary files. If such a scenario exists, surely it must be the exception rather than the norm. Why doesn't grep ignore binary files by default rather than requiring setting this flag to do so?

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You can set the variable GREP_OPTIONS to your preferred settings, then you don't have to use that many command line switches. –  Marco Mar 28 '13 at 16:02
A note for other commands that do not support such a variable: You can set default options by defining an alias in your .(ba|z|foo)shrc': alias grep="grep -I"`. –  Erik Mar 28 '13 at 19:19

1 Answer 1

up vote 26 down vote accepted

Not everything that grep thinks is a binary file, is actually a binary file. e.g. puppet's logs have ansi color coding in them, which makes grep think they're binary. I'd still want to search them if I'm grepping through /var/log though.

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The same goes for PDF files as well. –  Joseph R. Mar 28 '13 at 17:45
+ historically grep could NOT do that, so for compatibility only, default have to be all-inclusive. –  Olivier Dulac Mar 28 '13 at 18:54
@OlivierDulac it makes sense, otherwise ignoring binary files should be the default. –  Dagang Nov 25 '13 at 9:46

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