bug#43782: in egrep (grep 3.0), the order of include & exclude is surprisingly significant

[John Ruckstuhl]

> On 10/3/20 12:00 PM, John Ruckstuhl wrote:
> > In egrep (grep 3.0), the order of options (multiple --include and 
> > --exclude), is surprisingly significant.
> > I was puzzled by 5 extra output lines in my first egrep, so I did 
> > another egrep, with the --include moved up front.
>
> That's expected behavior, but it's not documented and should be. Thanks for 
> bringing it up. I installed the attached > doc patch.

Thank you for the quick response.
I looked at the patch, and for several minutes I was still not comprehending 
it...
But I think I've got it now.

This
    $ egrep -r -i -n -l --exclude="*.bak" --include="*.py" "$PAT" "$DIR"
does not map to this
    find "$DIR" -type f ! -name "*.bak" -name "*.py" |
    while read F; do egrep -i -n -l "$PAT" "$F"; done

It maps to this (with INCFIRST representing "-true" or "-false")
     find "$DIR" -type f \( \
         \( ! -name "*.bak" ! -name "*.py" \) \( \
             ! "$INCFIRST" \( -true \) \
             -o \
             "$INCFIRST" \( ! -name "*.bak" -name "*.py" \) \
         \) \
         -o \
             \( ! -name "*.bak" -name "*.py" \) \
     \) |
    while read F; do egrep -i -n -l "$PAT" "$F"; done

Yikes.
As it is not yet documented,
I'll happily venmo you $50 to consider it a bug instead of an undocumented 
behavior.
Warm regards, Paul.  :)
John Ruckstuhl


johnru@ISIMFGDEV400 /cygdrive/c/Program Files (x86)/foxtrot/EC Test SW 
(750390-mango)
$ egrep -r -i -n -l --exclude="*.bak" --include="*.py" "\.name\b|testname" 
ISITestFramework | cat -n
     1  ISITestFramework/DUT/CameraModule/CameraModule/CameraModule.py
     2  ISITestFramework/DUT/CameraModule/CameraModule/CameraModule_0.py
     3  ISITestFramework/DUT/EC/EC.py
     4  ISITestFramework/DUT/Endoscope/Endoscope.py
     5  ISITestFramework/DUT/GenericDUT.py
     6  ISITestFramework/DUT/LightEngine/LightEngine/LightEngine.py
!!   7  ISITestFramework/HTML/BatFileUtils.html
!!   8  ISITestFramework/HTML/Libs/jquery/1.12.2/jquery.min.js
     9  ISITestFramework/IQOQDQUtils.py
!!  10  ISITestFramework/Reports/ReportTemplates/Libraries/GoogleChartsJsapi.js
!!  11  ISITestFramework/Reports/ReportTemplates/Libraries/jquery-latest.min.js
!!  12  ISITestFramework/Reports/ReportTemplates/TestResultsSimple.html
    13  ISITestFramework/Reports/ReportTools.py
    14  ISITestFramework/Reports/ReportUtils.py
    15  ISITestFramework/Reports/SummaryMetricWriter.py
    16  ISITestFramework/Test.py
    17  ISITestFramework/TestTools.py

johnru@ISIMFGDEV400 /cygdrive/c/Program Files (x86)/foxtrot/EC Test SW 
(750390-mango)
$ egrep -r -i -n -l --include="*.py" --exclude="*.bak" "\.name\b|testname" 
ISITestFramework | cat -n
     1  ISITestFramework/DUT/CameraModule/CameraModule/CameraModule.py
     2  ISITestFramework/DUT/CameraModule/CameraModule/CameraModule_0.py
     3  ISITestFramework/DUT/EC/EC.py
     4  ISITestFramework/DUT/Endoscope/Endoscope.py
     5  ISITestFramework/DUT/GenericDUT.py
     6  ISITestFramework/DUT/LightEngine/LightEngine/LightEngine.py
     7  ISITestFramework/IQOQDQUtils.py
     8  ISITestFramework/Reports/ReportTools.py
     9  ISITestFramework/Reports/ReportUtils.py
    10  ISITestFramework/Reports/SummaryMetricWriter.py
    11  ISITestFramework/Test.py
    12  ISITestFramework/TestTools.py

this is the same logic:
$ for INCFIRST in -true -false; do
>     printf "%s: %s\n" "\$INCFIRST" "$INCFIRST"
>
>     # if no --incude or --exclude options match,
>     #   if not INCFIRST then file is included
>     #   if INCFIRST then file is not included
>     find "$DIR" -type f \( \
>         \( ! -name "*.bak" ! -name "*.py" \) \( \
>             ! "$INCFIRST" -true \
>             -o \
>             "$INCFIRST" \( ! -name "*.bak" -name "*.py" \) \
>         \) \
>         -o \
>             \( ! -name "*.bak" -name "*.py" \) \
>     \) |
>     # egrep "\.(html|js)$"
>     G | wc -l
> done
$INCFIRST: -true
12
$INCFIRST: -false
17