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How-to compile drbd-utils on ubuntu 14.04.4

Jeffrey Linux drbd

Ubuntu 上安装 drbd8-utils 之后 创建资源 失败。 查看版本信息 发现内核模块和用户空间的管理工具的版本不匹配 ubuntu14.4.04 kernel中编译的 drbd module 版本是 8.4.5, 而官方trusty所提供的drbd8-utils的版本只到8.4.4, 只能手动编译了

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How-to deploy flask web applications use wsgi behind apache

Jeffrey Dev Apache Flask

Flask是一个使用Python编写的轻量级Web应用框架。基于Werkzeug WSGI工具箱和Jinja2 模板引擎。 Flask使用BSD授权。 Flask也被称为“microframework”，因为它使用简单的核心，用extension增加其他功能。Flask没有默认使用的数据库、窗体验证工具。然而，Flask保留了扩增的弹性，可以用Flask-extension加入这些功能：ORM、窗体验证工具、文件上传、各种开放式身份验证技术。 WSGI Web服务器网关接口（Python Web Server Gateway Interface，缩写为WSGI）是为Python语言定义的Web服务器和Web应用程序或框架之间的一种简单而通用的接口。自从WSGI被开发出来以后，许多其它语言中也出现了类似接口。

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How-to resolve Target WSGI script xxx.wsgi cannot be loaded as Python module

Jeffrey Linux Apache Flask

情景再现： 在我将 Flask应用程序部署到 Apache 的时候，我得到了一个  500 internal sever error 的错误。 查看错误日志得到下面信息

[Tue Jun 21 11:29:46 2016] [notice] Apache/2.2.15 (Unix) DAV/2 PHP/5.3.3 mod_ssl/2.2.15 OpenSSL/1.0.1e-fips mod_wsgi/3.2 Python/2.7.3 mod_perl/2.0.4 Perl/v5.10.1 configured -- resuming #
[Tue Jun 21 11:29:49 2016] [error] [client 172.16.7.158] mod_wsgi (pid=1334): Target WSGI script '/var/www/html/report/report.wsgi' cannot be loaded as Python module.
[Tue Jun 21 11:29:49 2016] [error] [client 172.16.7.158] mod_wsgi (pid=1334): Exception occurred processing WSGI script '/var/www/html/report/report.wsgi'.
[Tue Jun 21 11:29:49 2016] [error] [client 172.16.7.158] Traceback (most recent call last):
[Tue Jun 21 11:29:49 2016] [error] [client 172.16.7.158]   File "/var/www/html/report/report.wsgi", line 10, in <module>
[Tue Jun 21 11:29:49 2016] [error] [client 172.16.7.158]     from report import app as application
[Tue Jun 21 11:29:49 2016] [error] [client 172.16.7.158]   File "/var/www/html/report/report.py", line 11, in <module>
[Tue Jun 21 11:29:49 2016] [error] [client 172.16.7.158]     from flask import Flask
[Tue Jun 21 11:29:49 2016] [error] [client 172.16.7.158] ImportError: No module named falsk

Python 应用程序是 通过源码编译的，安装目录为 /usr/local/Python2.7.3 Flask 模块是存在的， 问题就在 为啥 找不到她呢？？？

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Bytes-to-human and human-to-bytes converter

Jeffrey Dev Python 
#!/usr/bin/env python

"""
Bytes-to-human / human-to-bytes converter.
Based on: http://goo.gl/kTQMs
Working with Python 2.x and 3.x.

Author: Giampaolo Rodola' <g.rodola [AT] gmail [DOT] com>
License: MIT
"""

# see: http://goo.gl/kTQMs
SYMBOLS = {
    'customary'     : ('B', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y'),
    'customary_ext' : ('byte', 'kilo', 'mega', 'giga', 'tera', 'peta', 'exa',
                       'zetta', 'iotta'),
    'iec'           : ('Bi', 'Ki', 'Mi', 'Gi', 'Ti', 'Pi', 'Ei', 'Zi', 'Yi'),
    'iec_ext'       : ('byte', 'kibi', 'mebi', 'gibi', 'tebi', 'pebi', 'exbi',
                       'zebi', 'yobi'),
}

def bytes2human(n, format='%(value).1f %(symbol)s', symbols='customary'):
    """
    Convert n bytes into a human readable string based on format.
    symbols can be either "customary", "customary_ext", "iec" or "iec_ext",
    see: http://goo.gl/kTQMs

      >>> bytes2human(0)
      '0.0 B'
      >>> bytes2human(0.9)
      '0.0 B'
      >>> bytes2human(1)
      '1.0 B'
      >>> bytes2human(1.9)
      '1.0 B'
      >>> bytes2human(1024)
      '1.0 K'
      >>> bytes2human(1048576)
      '1.0 M'
      >>> bytes2human(1099511627776127398123789121)
      '909.5 Y'

      >>> bytes2human(9856, symbols="customary")
      '9.6 K'
      >>> bytes2human(9856, symbols="customary_ext")
      '9.6 kilo'
      >>> bytes2human(9856, symbols="iec")
      '9.6 Ki'
      >>> bytes2human(9856, symbols="iec_ext")
      '9.6 kibi'

      >>> bytes2human(10000, "%(value).1f %(symbol)s/sec")
      '9.8 K/sec'

      >>> # precision can be adjusted by playing with %f operator
      >>> bytes2human(10000, format="%(value).5f %(symbol)s")
      '9.76562 K'
    """
    n = int(n)
    if n < 0:
        raise ValueError("n < 0")
    symbols = SYMBOLS[symbols]
    prefix = {}
    for i, s in enumerate(symbols[1:]):
        prefix[s] = 1 << (i+1)*10
    for symbol in reversed(symbols[1:]):
        if n >= prefix[symbol]:
            value = float(n) / prefix[symbol]
            return format % locals()
    return format % dict(symbol=symbols[0], value=n)

def human2bytes(s):
    """
    Attempts to guess the string format based on default symbols
    set and return the corresponding bytes as an integer.
    When unable to recognize the format ValueError is raised.

      >>> human2bytes('0 B')
      0
      >>> human2bytes('1 K')
      1024
      >>> human2bytes('1 M')
      1048576
      >>> human2bytes('1 Gi')
      1073741824
      >>> human2bytes('1 tera')
      1099511627776

      >>> human2bytes('0.5kilo')
      512
      >>> human2bytes('0.1  byte')
      0
      >>> human2bytes('1 k')  # k is an alias for K
      1024
      >>> human2bytes('12 foo')
      Traceback (most recent call last):
          ...
      ValueError: can't interpret '12 foo'
    """
    init = s
    num = ""
    while s and s[0:1].isdigit() or s[0:1] == '.':
        num += s[0]
        s = s[1:]
    num = float(num)
    letter = s.strip()
    for name, sset in SYMBOLS.items():
        if letter in sset:
            break
    else:
        if letter == 'k':
            # treat 'k' as an alias for 'K' as per: http://goo.gl/kTQMs
            sset = SYMBOLS['customary']
            letter = letter.upper()
        else:
            raise ValueError("can't interpret %r" % init)
    prefix = {sset[0]:1}
    for i, s in enumerate(sset[1:]):
        prefix[s] = 1 << (i+1)*10
    return int(num * prefix[letter])

Extra: for an alternative version as simple as possible (no global vars, no extra args, easier to customize) see here: http://code.google.com/p/pyftpdlib/source/browse/trunk/test/bench.py?spec=svn984&r=984#137

 

来自 http://code.activestate.com/recipes/578019-bytes-to-human-human-to-bytes-converter/

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Couchbase CLI Notes

Jeffrey Linux couchbase

cbreset_password

Syntax

The basic syntax to reset the administrative password:

cbreset_password [hostname]:[port]

#./bin/cbreset_password 127.0.0.1:8091
Please enter the new administrative password (or <Enter> for system generated password):
Running this command will reset administrative password.
Do you really want to do it? (yes/no)yes
Resetting administrative password...
Password for user Administrator was successfully replaced.

未完待续  ...

 

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Bash Arrays

Jeffrey Linux shell

如果你使用的是类UNIX的shell 你可能对bash 的 数组不是很熟悉。虽然没有向P语言(Perl, Python, PHP)那样强大，但是它们往往是很有用处的。 Bash 数组只有索引编号，但是它们是单独的。也就是说你不必定义所有索引。整个数组可以通过封闭括号中的数组项分配：

arr=(Hello World)

单个项目可以用熟悉的数组语法被分配（除非你已经习惯了Basic或Fortran）：

  arr[0]=Hello
  arr[1]=World

但是，当你要引用数组项它变得有点难看：

  echo ${arr[0]} ${arr[1]}

man 手册中的部分内容： 大括号是必需的，以避免与路径扩展冲突。

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How-to use dot to draw flow chart

Jeffrey Linux

Graphviz （Graph Visualization Software的缩写） 是AT Labs-Research开发的图形绘制工具,他可以很方便的用来绘制结构化的图形网络,支持多种格式输出,生成图片的质量和速度都不错.Graphviz本身是开源的产品,下载可以到 这里,以及他的演示界面 Graphviz在windows上和Linux上都可以顺利运行.它的强大主要体现在“所思即所得"（WYTIWYG，what you think is what you get），这是和office的“所见即所得“（WYSIWYG，what you see is what you get）完全不同的一种方式。

graphviz中包含了众多的布局器：

  1. dot 默认布局方式，主要用于有向图
  2. neato 基于spring-model(又称force-based)算法
  3. twopi 径向布局
  4. circo 圆环布局
  5. fdp 用于无向图

graphviz的设计初衷是对有向图/无向图等进行自动布局，开发人员使用dot脚本定义图形元素，然后选择算法进行布局，最终导出结果。

使用graphviz的一般流程为：

  1. 定义一个图，并向图中添加需要的顶点和边
  2. 为顶点和边添加样式
  3. 使用布局引擎进行绘制

基础知识

graphviz包含3种元素，图，顶点和边。每个元素都可以具有各自的属性，用来定义字体，样式，颜色，形状等。下面是一些简单的示例，可以帮助我们快速的了解graphviz的基本用法。

图的属性

map_attributes

节点属性

node_attributes

边属性

node_attributes

Ubuntu 安装 Graphviz

sudo apt-get  install  graphviz -y

dot usage

dot -?
Usage: dot [-Vv?] [-(GNE)name=val] [-(KTlso)<val>] <dot files>
(additional options for neato)    [-x] [-n<v>]
(additional options for fdp)      [-L(gO)] [-L(nUCT)<val>]
(additional options for memtest)  [-m<v>]
(additional options for config)  [-cv]

 -V          - Print version and exit
 -v          - Enable verbose mode 
 -Gname=val  - Set graph attribute 'name' to 'val'
 -Nname=val  - Set node attribute 'name' to 'val'
 -Ename=val  - Set edge attribute 'name' to 'val'
 -Tv         - Set output format to 'v'
 -Kv         - Set layout engine to 'v' (overrides default based on command name)
 -lv         - Use external library 'v'
 -ofile      - Write output to 'file'
 -O          - Automatically generate an output filename based on the input filename with a .'format' appended. (Causes all -ofile options to be ignored.) 
 -P          - Internally generate a graph of the current plugins. 
 -q[l]       - Set level of message suppression (=1)
 -s[v]       - Scale input by 'v' (=72)
 -y          - Invert y coordinate in output

 -n[v]       - No layout mode 'v' (=1)
 -x          - Reduce graph

 -Lg         - Don't use grid
 -LO         - Use old attractive force
 -Ln<i>      - Set number of iterations to i
 -LU<i>      - Set unscaled factor to i
 -LC<v>      - Set overlap expansion factor to v
 -LT[*]<v>   - Set temperature (temperature factor) to v

 -m          - Memory test (Observe no growth with top. Kill when done.)
 -m[v]       - Memory test - v iterations.

 -c          - Configure plugins (Writes $prefix/lib/graphviz/config 
               with available plugin information.  Needs write privilege.)
 -?          - Print usage and exit

 

待续 ...

 

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