Shell script Trim 관련 질문드립니다.

$ perl -e 'print "\xab\xcd\xef\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"' > binary
 
$ od -t x1 binary
0000000 ab cd ef ff ff ff ff ff ff ff ff ff ff ff ff
0000017

$ perl -p00i -e 's/\xff+$//' binary
 
$ od -t x1 binary
0000000 ab cd ef
0000003

$ perl -e 'print( ("\xaa"x100000000)."\xab\xcd\xef\xff\xff\xff\xff\x0a\xff\xff\xff\xff\xff\xff\xff\xff")' > binary
$ ls -lah binary
-rw-r--r-- 1 aero aero 96M 2010-11-10 22:15 binary
$ time perl -p00i -e 's/\xff+$//' binary
 
real    0m0.540s
user    0m0.310s
sys     0m0.230s

#!/usr/bin/env perl
use strict;
use warnings;
 
open my $fh, '+<', $ARGV[0];
seek $fh, 0, 2;
while ( tell $fh > 0 ) {
    seek $fh, -1, 1;
    read $fh, my $char, 1;
    if ( $char !~ "\xff" ) {
        truncate $fh, tell($fh);
        close $fh;
        last;
    }
    seek $fh, -1, 1;
}

$ time perl test.pl binary
 
real    0m0.006s
user    0m0.010s
sys     0m0.000s

perl -p00i -e 's{\xff*$}{}s' file