Perl: Math::Round

Perl installation

• Perl installation if it wasn't previously installed:

apt-get install perl

• Perl Math Round library installation:

apt-get install libmath-round-perl

• AppConfig and DBI perl modules installation:

apt-get install libappconfig-perl libdbi-perl

nearest TARGET, LIST

Rounds the number(s) to the nearest multiple of the target value. TARGET must be positive. In scalar context, returns a single value; in list context, returns a list of values. Numbers that are halfway between two multiples of the target will be rounded to infinity. For example:

  nearest(10, 44)    yields  40
nearest(10, 46)            50
nearest(10, 45)            50
nearest(25, 328)          325
nearest(.1, 4.567)          4.6
nearest(10, -45)          -50

===========================================

#!/usr/local/bin/perl
  use POSIX qw(ceil floor);

  $num = 42.4;  # The Answer to the Great Question (on a Pentium)!

  print "Floor returns: ", floor($num), "\n";
  print "Ceil returns:  ", ceil($num), "\n";

Ubuntu: Use bandwidth monitor to output traffic file

bwm-ng -o csv -c 0 -F bd.csv

The Disk Usage Analyzer

Ubuntu: Checking folder size

In the target folder:

du -chks

Other: du -hs folderpath

Perl: Term::ANSIColor

print color("red"), "Text is red\n", color("reset"); print RED "Text is red\n", RESET;

• Foreground colors

   30    Black
  31    Red
  32    Green
  33    Yellow
  34    Blue
  35    Magenta
  36    Cyan
  37    White

• Background colors

   40    Black
  41    Red
  42    Green
  43    Yellow
  44    Blue
  45    Magenta
  46    Cyan
  47    White

Perl: Cross pl variable, hashtable, array

$ cat test.pl
use strict;

require "test2.pl";

our $variable;
print $variable;

$ cat test2.pl
our $variable = 42;

$perl test.pl
42

-------------------------
**
headers.pl
**
our @arr = ();
our $ht = {};
push($arr, "A");
$ht->{"A"} = "value";

**
main.pl
**
require "headers.pl";
our @arr;
our $ht;

print scalar(@arr)."\n";
print "$ht->{$arr[0]}";

ls如何只是輸出directory而不是file

ls如何只是輸出directory而不是file 不知道為什麼我的fbsd的ls -d 只是輸出"."?

ls如何只是輸出directory而不是file ls -ld */

ls如何只是輸出directory而不是file 好，比我的解決方案好多了： ls -lp | grep /

ls如何只是輸出directory而不是file ls -l|grep ^d

ls如何只是輸出directory而不是file ls -l | awk '$1 ~ /^d/ {print $9}' linux system

ls如何只是輸出directory而不是file --> ls -al | sed -n '/^d/p'

ls如何只是輸出directory而不是file 都不如頭一個解決方案好。

ls如何只是輸出directory而不是file [code]file *|grep directory[/code]

ls如何只是輸出directory而不是file --> 這個特別. 8)

ls如何只是輸出directory而不是file ls -d */

ls如何只是輸出directory而不是file ls -F |grep '\/$'

ls如何只是輸出directory而不是file 還是#ls -l |grep ^d 好，各個系統通用。

Ref: http://www.lslnet.com/linux/f/docs1/i30/big5237499.htm