buggrep - Bugs: bug #36831, single character swallowed in...

 
 

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bug #36831: single character swallowed in output

Submitted by:  None
Submitted on:  Thu Jul 12 07:34:58 2012  
 
Category: NoneSeverity: 3 - Normal
Item Group: NoneStatus: None
Privacy: PublicAssigned to: None
Open/Closed: Open

Thu Jan 2 19:28:29 2014, comment #3:

the source code has a very long explanation on the topic:
http://git.savannah.gnu.org/cgit/grep.git/tree/src/main.c?id=88d65410f7aa472c66da1bdf01c3cc1439cefce6#n142

with the simple workaround:
export GREP_COLORS=ne

simpler test case is:
printf '%*s\n' $COLUMNS X | grep --color=always X

i also think this is a dup of bug 25539

Mike Frysinger <vapier>
Sat Jul 20 00:03:43 2013, comment #2:

Looking into this, it's definitely the same problem. When grep is in color mode it outputs the control sequence

unmatched text ^[[01;31m^[[Kmatched text^[[m^[[K^M

If the matched text goes to the end of line, by the vt100 spec the cursor remains at the end of line on the last character. This means the subsequent ^[[K (erase from cursor to end of line) erases the last character of the matched text. This depends on the terminal, gnome-terminal and konsole treat the erase to end of line differently after writing the last character on the current line.

Does anyone know why the erase to end of line is necessary, given when in no color mode grep just prints "unmatched text matched text^M" with no erase codes? Removing these should fix the problem on all terminals.

Robert Flack <flackr>
Fri Jul 19 22:07:47 2013, comment #1:

I've been seeing a similar issue which is perhaps the same. If you run the following command but substitute your terminal width in characters for XXX the colored "1" is missing from the output in most terminals (except for gnome-terminal).

printf "%0XXXd test\n" 1|grep 1

Robert Flack <flackr>
Thu Jul 12 07:34:58 2012, original submission:

In one of multiple lines of output grep swallowed one character from an instance of the searched word (see last but two line in attached screenshot).

This doesn't happen when --color=never is given on the command line.

Anonymous

 

Attached Files
file #26183:  grep-bug-or-feature.png added by None (23kB - image/png)

 

Depends on the following items: None found

Items that depend on this one: None found

 

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  • -unavailable- added by vapier (Posted a comment)
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  • -unavailable- added by flackr (Posted a comment)
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    Follow 2 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Thu Jan 2 19:28:29 2014vapierCarbon-Copy-=>Added -unavailable-
    Thu Jul 12 07:34:58 2012NoneAttached File-=>Added grep-bug-or-feature.png, #26183

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