"grep -rI ... /" vs. processing of /dev/ : should "--exclude-dir /dev" be required in order to avoid /dev/?

Mark Millard marklmi at yahoo.com
Wed Feb 17 22:26:43 UTC 2021


On 2021-Feb-17, at 11:44, Kyle Evans <kevans at freebsd.org> wrote:

> On Tue, Feb 16, 2021 at 7:29 PM Kyle Evans <kevans at freebsd.org> wrote:
>> 
>> On Tue, Feb 16, 2021 at 7:23 PM Mark Millard via freebsd-current
>> <freebsd-current at freebsd.org> wrote:
>>> 
>>> I historically on occasion have done something like:
>>> 
>>> # grep -rI ... /
>>> 
>>> in order to find all instances of a text, including
>>> in build trees and such. I now find that I need to
>>> do something more like (using a more specific
>>> example):
>>> 
>>> # grep -rI --exclude-dir /dev '#define.*__FreeBSD_version'
>>> 
>>> otherwise the grep ends up reading from the tty and waits
>>> for it. Top shows, for example,
>>> 
>>> 13470 root         22    0  12848Ki    2692Ki ttyin   11   0:00   0.00% grep -rI #define.*__FreeBSD_version /
>>> 
>>> Is this expected? Should I have always been using
>>> "--exclude-dir /dev"? What lead to the behavior
>>> change?
>>> 
>> 
>> I can't seem to find any evidence that gnugrep in base handled this
>> any differently. Experimentation seems to reveal that modern gnugrep
>> will skip devices unless they're explicitly named for searching
>> (unless supplied a different --devices option), which does feel like a
>> good idea.
> 
> Here's my proposal: https://people.freebsd.org/~kevans/grep-rdev.diff

wget, git apply, buildworld, installworld, and some quick testing:

Seems to work as described in the updated man page and avoids my
needing "--exclude-dir /dev" (or other alternatives) by default
with the -r .

I did try some explicit /dev and /dev/tty and /dev/random use,
and some "no -r" variations of the -r testing. While it was
just quick testing, I did not notice anything odd happening.
I did do one -r for / that I let run to completion.



FYI: this is based on main 3acea07c1873 as a context. In
more detail:

# ~/fbsd-based-on-what-freebsd-main.sh 
merge-base: 3acea07c1873b1e4042f4a4fa8668745ee59f15b
merge-base: CommitDate: 2021-02-08 19:15:21 +0000
c1845d00f818 (HEAD -> mm-src) mm-src snapshot for mm's patched build in git context.
3acea07c1873 (pure-src) Restore the augmented strlen commentary
FreeBSD FBSDFHUGE 14.0-CURRENT FreeBSD 14.0-CURRENT mm-src-n244686-c1845d00f818 GENERIC-NODBG  amd64 amd64 1400004 1400004


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)



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