文件操作符|-e|-M|-s|-A|_|-r -w $filename|stat|localtime|&|>>|<<

TTY:终端是一种字符型设备，它有多种类型，通常使用tty 来简称各种类型的终端设备

 #!/usr/bin/perl

 use strict;
 use warnings;

 print "exist!\n" if -e '1.txt';
 print "exist!\n" if -e '2.txt';

 #exist!
 #

 warn "new file!\n" if -M '1.txt' < ;

 #new file!

 my $filename = '1.txt';
 if((-s $filename <100_000) &&(-A _ < )){print "this file is small and new!\n";}
 if(-w -r _ ){print "this file is both writable and readable!\n";}

 #this file is small and new!
 #this file is both writable and readable!

 my $file = -s $filename;print "file size is $file"."B\n";

 #file size is 116B

 if (-l 'check.pl'){print "check.pl is a file with link\n"}

 #check.pl is a file with link

 my $M = -M '1.txt';my $C = -C 'check.pl';my $A = -A 'check.pl';print "$M\t$C\t$A\n";

 #0.0313657407407407407   3.10847222222222222     3.10847222222222222

 $_ ='1.txt';if (-r){print "$_ is a readhandle\n"}

 #1.txt is a readhandle

 my $size = (-s)/;print "$size\n";

 #0.11328125

 my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks) = stat('1.txt');$atime = localtime $atime;
 my ($sec,$min,$hour,$day,$mon,$year,$wday,$yday,$isdst)=localtime $ctime;
 print "dev_number=$dev\ninode =$ino\nmode=$mode\nhard link=$nlink\nuser id=$uid\ngroup id=$gid\n$rdev\nsize=$size\n$atime\n$mtime\n$ctime\n$blksize\n$blocks\n";
 print "$yday\n";

 #dev_number=43
 #inode =95085688861
 #mode=33188
 #hard link=1
 #user id=1000092
 #group id=30086
 #0
 #size=116
 #Sun Jun 30 17:17:20 2019
 #1561886240
 #1561886240
 #1048576
 #8
 #180

 my $now =gmtime;print "$now\n";

 #Sun Jun 30 11:10:25 2019

 my $two = &;print "$two\n";
 my $move = 25.5>>;print "$move\n";
 $move = (>>)<<;print "$move\n";

 #0
 #6
 #24