Re: sed: dot does not match newline in multi-line mode (the M modifier) - bug or feature?

[Thierry Blanc]

On 11/23/2011 05:36 PM, Paolo Bonzini wrote:
> echo $'line1\nline2\nline3' | sed -n '1h;1!H;$bend;b; :end g;s/.*/dot
> >  matches newline/;p; g;s/.*/dot does not match newline/M;p'
`M'
`m'
     The `M' modifier to regular-expression matching is a GNU `sed'
     extension which causes `^' and `$' to match respectively (in
     addition to the normal behavior) the empty string after a newline,
     and the empty string before a newline.  There are special character
     sequences (`\`' and `\'') which always match the beginning or the
     end of the buffer.  `M' stands for `multi-line'.

the M or m option seems to match also ..

address@hidden:~/sed$ echo $'line1\nline2\nline3' | sed -n 
'1h;1!H;$bend;b; :end g;s/^/dot matches newline/M;p'
dot matches newlineline1
line2
line3

address@hidden:~/sed$ echo $'line1\nline2\nline3' | sed -n 
'1h;1!H;$bend;b; :end g;s/$/dot matches newline/M;p'
line1dot matches newline
line2
line3
address@hidden:~/sed$ echo $'line1\nline2\nline3' | sed -n 
'1h;1!H;$bend;b; :end g;s/\`/BEGINofBUFFFER:/m;p'
BEGINofBUFFFER:line1
line2
line3
address@hidden:~/sed$ echo $'line1\nline2\nline3' | sed -n 
'1h;1!H;$bend;b; :end g;s/'"\'"'/:ENDofBUFFFER/m;p'
line1
line2
line3:ENDofBUFFFER