Reproducer: $ printf 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx1234xxxxxxxxx\n' | grep 1234 --color=always xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx123xxxxxxxxx
This can be reproduced at least on xterm and linux console, but it works on xfce4-terminal and konsole (at least). The EL command (\E[K) is sent to clear the line. The VT100 terminal autowraps when the 81th character is received and the EL command is not counted as a character. So if 80 characters are received, it waits on the 80th character and the following EL command erases characters from the current one to the end of line (i.e. the last character on the line). Workaround is to use GREP_COLORS=ne. The original Red Hat bugzilla that contains discussion with the xterm upstream: http://bugzilla.redhat.com/show_bug.cgi?id=1006310
