第十一章：文件测试

1)
use warnings;
foreach(@ARGV){
 if (-e){ # -e means -e $_
  print "$_ exists.\n";
 } else{
  print "$_ Not exists.\n";
 }
 if (-r){
  print "$_ is readable.\n";
 } else{
  print "$_ is Not readable.\n";
 }
 if (-w){
  print "$_ is writable.\n";
 } else{
  print "$_ is Not writable.\n";
 }
 if (-x){
  print "$_ is executable.\n";
 } else{
  print "$_ is Not executable.\n";
 }
}

2)
use warnings;
die "No file names supplied!\n" unless @ARGV;
my @files;
my $oldest;
my $days;
foreach(@ARGV){
 if(-e){
  push @files, $_;
 } 
}
foreach(@files){
 $days = -M;
 $oldest = $_ if $oldest < $days;
}
printf "The oldest file was %s, and it was %.f days old.\n", $oldest, $days;