libitte

var array = [
2,
4,
8,
16,
32,
64,
128,
256,
512,

libitte

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git reset --hard HEAD^

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libitte

#!/usr/bin/env perl
use strict;
use warnings;

print "- system\n";
print "-----------------\n";
my $ret_sys = system 'ps aux | grep -v grep | grep perl | wc -l';
print '$ret_sys is ', $ret_sys;
print "\n";
print "-----------------\n";

libitte

#!/usr/bin/env perl
use strict;
use warnings;
use Perl6::Say;

use Data::Dumper;
#use List::Util qw( shuffle );
use Digest::MD5 qw(md5_hex);

my $KEY = 'bra-bra';

libitte

#!/usr/bin/env perl
use strict;
use warnings;
use Perl6::Say;

use Data::Dumper;
local $Data::Dumper::Indent = 1;
local $Data::Dumper::Terse = 1;

use Digest::MD5 qw(md5_hex);

libitte

#!/usr/bin/env perl
use strict;
use warnings;

use Data::Dumper;

my %hash = (
        key1 => 'value1',
        key2 => 'value2',
        key3 => 'value3',

libitte

VIM

In Vi Improved to change or set desired syntax highlighting mode to MODE you have to type in VIM's command line:

:set syntax=MODE


It is very usefull when your file does not have standard extension or you are editting file with two languages in it, eg. AWK commands in a BASH script.

You can set AWK mode	:set syntax=awk

libitte

what's the difference between “hadoop fs” shell commands and “hdfs dfs” shell commands?

fs refers to any file system, it could be local or HDFS but dfs refers to only HDFS file system.

http://stackoverflow.com/questions/18142960/whats-the-difference-between-hadoop-fs-shell-commands-and-hdfs-dfs-shell-co

Differnce between hadoop dfs and hadoop fs

You can see definitions of the two commands (hadoop fs & hadoop dfs) in $HADOOP_HOME/bin/hadoop

libitte

• 配列の差分

@A - @B

my @A = qw(1 2 3 4 5 6 7 8 9);
my @B = qw(3 5 9);
 
my %cnt = ();
map { $cnt{$_}-- } @B;

libitte

user ごとの 件数のうち最大件数をしらべる

• select-max-from-count

SELECT MAX(counted) FROM
(
SELECT COUNT(*) AS counted
FROM table_actions
WHERE status = "good"