Shell Programming and Scripting

M1  I
M1 have
M1 a 
M1 file
M1 consisting
M1 of
M1 lines
M1 in 
M1 such
M1 a
M1 format
M1 EOS
M2 This
M2 is 
M3 an
M3 example
M3 EOS

 open my $M_IN, "<:encoding(utf8)", "$ARGV[0]" or die "Can't open file $ARGV[0]: $!";
 while(my $my_input= <$M_IN>)
        {
                @m_input_text= split /\s+/, $my_input;
                
        }

perl -i -pe 's/^M. //g' file

$
$
$ cat data.txt
M1  I
M1 have
M1 a
M1 file
M1 consisting
M1 of
M1 lines
M1 in
M1 such
M1 a
M1 format
M1 EOS
M2 This
M2 is
M3 an
M3 example
M3 EOS
$
$ perl -ne '{chomp; s/^M\d[ ]+//g; s/[ ]*$//; $x .= " ".$_}
            END {$x =~ s/^ //; $x =~ s/ EOS[ ]*/.\n/g; print $x}' data.txt
I have a file consisting of lines in such a format.
This is an example.
$
$

awk '/^M[0-9]+[ \t]+/&&$2!="EOS"{printf("%s ",$2)}$2=="EOS"{printf(".\n")}' data.txt| sed 's/ \.$/./'