在Perl中,如何在文件中更改,删除或插入行,或者附加到文件的开头？

open(my $file, '<', 'filename.txt') or die "Cannot open file: $!";
my @lines = <$file>;
close($file);

# 修改第3行的内容
$lines[2] = "New line content\n";

open($file, '>', 'filename.txt') or die "Cannot open file: $!";
print $file @lines;
close($file);

open(my $file, '<', 'filename.txt') or die "Cannot open file: $!";
my @lines = <$file>;
close($file);

# 删除包含特定关键字的行
@lines = grep { !/keyword/ } @lines;

open($file, '>', 'filename.txt') or die "Cannot open file: $!";
print $file @lines;
close($file);

open(my $file, '<', 'filename.txt') or die "Cannot open file: $!";
my @lines = <$file>;
close($file);

# 在第2行后插入新行
splice(@lines, 2, 0, "New line content\n");

open($file, '>', 'filename.txt') or die "Cannot open file: $!";
print $file @lines;
close($file);

open(my $file, '<', 'filename.txt') or die "Cannot open file: $!";
my @lines = <$file>;
close($file);

# 在开头附加新行
unshift(@lines, "New line content\n");

open(my $temp, '>', 'tempfile.txt') or die "Cannot open file: $!";
print $temp @lines;
close($temp);

rename('tempfile.txt', 'filename.txt') or die "Cannot rename file: $!";