Why do I get “Binary file matches” with grep -I?





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5















In the following example, grep behaves strangely: it's supplied with -I option, which, according to man page, should make grep ignore binary files (similarly to --binary-files=without-match), but I still get the "Binary file matches" output.



$ cat <<'EOF' | uudecode > test-file
begin 664 /dev/stdout
M>`&5SLU*Q$`0!&#/>8J^"TM/=^8/1%2>1`>.^9Z=D-9!))9@7?WBB^@%"G
MHOBHO+8V=2!'-WU3A9PX%*8PBB:VGK@6)Y*HFAB(.2;.;$SQPX=LNG3(>2SH
MDJE!5;R+E9P21J::8U2+?@R>RK&7:[^L&[Q=]UD6>)$D?9<O_82[Y$&S4_,
MP[G)-)_RVN[!6(S.>F0/MB(P]$>5[O^%_$8+/(?,CSI+]%DD;/"^^,K3`OD
,6?8=GK6MPS?WDU!"
`
end
EOF
$ grep -I 8 test-file
Binary file test-file matches
$ grep --binary-files=without-match 8 test-file
Binary file test-file matches


Apparently, grep considers the file binary, but still does try to match and reports the results with it. Why is the "binary file" not ignored as the -I option prescribes?



I'm using GNU grep 3.1 on Ubuntu 18.04.










share|improve this question





























    5















    In the following example, grep behaves strangely: it's supplied with -I option, which, according to man page, should make grep ignore binary files (similarly to --binary-files=without-match), but I still get the "Binary file matches" output.



    $ cat <<'EOF' | uudecode > test-file
    begin 664 /dev/stdout
    M>`&5SLU*Q$`0!&#/>8J^"TM/=^8/1%2>1`>.^9Z=D-9!))9@7?WBB^@%"G
    MHOBHO+8V=2!'-WU3A9PX%*8PBB:VGK@6)Y*HFAB(.2;.;$SQPX=LNG3(>2SH
    MDJE!5;R+E9P21J::8U2+?@R>RK&7:[^L&[Q=]UD6>)$D?9<O_82[Y$&S4_,
    MP[G)-)_RVN[!6(S.>F0/MB(P]$>5[O^%_$8+/(?,CSI+]%DD;/"^^,K3`OD
    ,6?8=GK6MPS?WDU!"
    `
    end
    EOF
    $ grep -I 8 test-file
    Binary file test-file matches
    $ grep --binary-files=without-match 8 test-file
    Binary file test-file matches


    Apparently, grep considers the file binary, but still does try to match and reports the results with it. Why is the "binary file" not ignored as the -I option prescribes?



    I'm using GNU grep 3.1 on Ubuntu 18.04.










    share|improve this question

























      5












      5








      5








      In the following example, grep behaves strangely: it's supplied with -I option, which, according to man page, should make grep ignore binary files (similarly to --binary-files=without-match), but I still get the "Binary file matches" output.



      $ cat <<'EOF' | uudecode > test-file
      begin 664 /dev/stdout
      M>`&5SLU*Q$`0!&#/>8J^"TM/=^8/1%2>1`>.^9Z=D-9!))9@7?WBB^@%"G
      MHOBHO+8V=2!'-WU3A9PX%*8PBB:VGK@6)Y*HFAB(.2;.;$SQPX=LNG3(>2SH
      MDJE!5;R+E9P21J::8U2+?@R>RK&7:[^L&[Q=]UD6>)$D?9<O_82[Y$&S4_,
      MP[G)-)_RVN[!6(S.>F0/MB(P]$>5[O^%_$8+/(?,CSI+]%DD;/"^^,K3`OD
      ,6?8=GK6MPS?WDU!"
      `
      end
      EOF
      $ grep -I 8 test-file
      Binary file test-file matches
      $ grep --binary-files=without-match 8 test-file
      Binary file test-file matches


      Apparently, grep considers the file binary, but still does try to match and reports the results with it. Why is the "binary file" not ignored as the -I option prescribes?



      I'm using GNU grep 3.1 on Ubuntu 18.04.










      share|improve this question














      In the following example, grep behaves strangely: it's supplied with -I option, which, according to man page, should make grep ignore binary files (similarly to --binary-files=without-match), but I still get the "Binary file matches" output.



      $ cat <<'EOF' | uudecode > test-file
      begin 664 /dev/stdout
      M>`&5SLU*Q$`0!&#/>8J^"TM/=^8/1%2>1`>.^9Z=D-9!))9@7?WBB^@%"G
      MHOBHO+8V=2!'-WU3A9PX%*8PBB:VGK@6)Y*HFAB(.2;.;$SQPX=LNG3(>2SH
      MDJE!5;R+E9P21J::8U2+?@R>RK&7:[^L&[Q=]UD6>)$D?9<O_82[Y$&S4_,
      MP[G)-)_RVN[!6(S.>F0/MB(P]$>5[O^%_$8+/(?,CSI+]%DD;/"^^,K3`OD
      ,6?8=GK6MPS?WDU!"
      `
      end
      EOF
      $ grep -I 8 test-file
      Binary file test-file matches
      $ grep --binary-files=without-match 8 test-file
      Binary file test-file matches


      Apparently, grep considers the file binary, but still does try to match and reports the results with it. Why is the "binary file" not ignored as the -I option prescribes?



      I'm using GNU grep 3.1 on Ubuntu 18.04.







      grep binary






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Apr 2 at 10:22









      RuslanRuslan

      1,3841427




      1,3841427






















          1 Answer
          1






          active

          oldest

          votes


















          8














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





          share|improve this answer
























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            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            8














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





            share|improve this answer




























              8














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





              share|improve this answer


























                8












                8








                8







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





                share|improve this answer













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






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Apr 2 at 10:41









                murumuru

                37.3k589164




                37.3k589164






























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