BlogJava-miaoyachun-随笔分类-Skills

树莓派3B完美匹配DELL P2014H的配置

Milo的海域 — Wed, 15 Jun 2016 01:32:00 GMT

默认的配置有时候点不亮显示器，且分辨率很低，通过tvservice工具不断调试，发现下面的参数可以完美匹配了
修改 /boot/config.txt的下列参数

disable_overscan=1
hdmi_force_hotplug=1
hdmi_group=1
hdmi_mode=16
hdmi_drive=2
config_hdmi_boost=4
dtparam=audio=on

Milo的海域 2016-06-15 09:32 发表评论

一些项目中用到的mvn例子

Milo的海域 — Thu, 10 Jan 2013 05:33:00 GMT

mvn 执行外部命令
命令行模式

mvn exec:exec -Dexec.executable=sh -Dexec.workingdir=./bin -Dexec.args=hello.sh

配置文件形式

                                org.codehaus.mojo
                                exec-maven-plugin


                                                test-exec
                                                initialize

                                                        sh
                                                        ./bin

                                                                hello.sh



                                                        exec

mvn 生成java项目
生成骨架

mvn archetype:generate -DgroupId=com.abc.product -DartifactId=product -DpackageName=com.abc.product -DarchetypeArtifactId=maven-archetype-quickstart

转成eclipse能识别的java 项目

mvn eclipse:eclipse

导入eclipse 然后coding

mvn进行单元测试

                                org.apache.maven.plugins
                                maven-surefire-plugin
                                2.12.4

                                        pertest

                                                **/perftest/*.java



                                                        log4j.configuration
                                                        target/test-classes/log4j.properties

mvn进行code coverage统计

        org.codehaus.mojo
        emma-maven-plugin
        1.0-alpha-3
        true


        org.codehaus.mojo
        surefire-report-maven-plugin
        true

mvn生成javadoc

                                org.apache.maven.plugins
                                maven-javadoc-plugin
                                2.9

                                        private



                                                attach-javadocs

                                                        javadoc
                                                        test-javadoc

                                                site

Milo的海域 2013-01-10 13:33 发表评论

Perlvar

Milo的海域 — Thu, 21 Jun 2012 09:10:00 GMT

Perl里面的predefined vars

perlvar

用perldoc perlvar 可以结合实例来了解更详细的信息。

下面针对$@写了个perl alarm的例子

#!/usr/bin/perl

my $timeout = 5;

$SIG{ALRM} = sub {
    die "alarm\n";
};

eval {
    alarm $timeout;
    sleep(6);
    alarm 0;
};

if ($@) {
    print "timeout\n";
}
else {
    print "not timeout\n";
}

Milo的海域 2012-06-21 17:10 发表评论

项目依赖分析工具

Milo的海域 — Wed, 13 Jun 2012 08:13:00 GMT

zane昨天推荐个项目依赖分析的工具: http://www.jboss.org/tattletale

JBoss Tattletale is a tool that can help you get an overview of the project you are working on
or a product that you depend on.

The tool will provide you with reports that can help you

* Identify dependencies between JAR files
* Find missing classes from the classpath
* Spot if a class/package is located in multiple JAR files
* Spot if the same JAR file is located in multiple locations
* With a list of what each JAR file requires and provides
* Verify the SerialVersionUID of a class
* Find similar JAR files that have different version numbers
* Find JAR files without a version number
* Find unused JAR files
* Identify sealed / signed JAR archives
* Locate a class in a JAR file
* Get the OSGi status of your project

使用方法

java -Xmx512m -jar tattletale.jar [-exclude=]

[output-directory]

注意事项

tattletale只分析jar包之间的依赖，需要自己把所有的class文件打包放入scan-directory，然后把依赖的lib也放入同个目录

Milo的海域 2012-06-13 16:13 发表评论

Statistics of code line for project

Milo的海域 — Thu, 31 May 2012 07:32:00 GMT

A tool cloc which wrote by perl could help u do that:

http://cloc.sourceforge.net/

prompt> cloc perl-5.10.0.tar.gz
    4076 text files.
    3883 unique files.
    1521 files ignored.

http://cloc.sourceforge.net v 1.50  T=12.0 s (209.2 files/s, 70472.1 lines/s)
-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
Perl                          2052         110356         130018         292281
C                              135          18718          22862         140483
C/C++ Header                   147           7650          12093          44042
Bourne Shell                   116           3402           5789          36882
Lisp                             1            684           2242           7515
make                             7            498            473           2044
C++                             10            312            277           2000
XML                             26            231              0           1972
yacc                             2            128             97           1549
YAML                             2              2              0            489
DOS Batch                       11             85             50            322
HTML                             1             19              2             98
-------------------------------------------------------------------------------
SUM:                          2510         142085         173903         529677
-------------------------------------------------------------------------------

Here is command line example:

Usage: cloc-1.56.pl [options] | 1> 2> |

Milo的海域 2012-05-31 15:32 发表评论

About cannot core dump after setuid on linux server

Milo的海域 — Wed, 30 May 2012 07:32:00 GMT

In many cases, binaries can no longer dump core after calling setuid(). 
Under Linux it is possible to re-enable this with a system call.

e.g.

+#ifdef __linux__
+#include <sys/prctl.h>
+#endif
+
#ifdef HAVE_purify
#define IF_PURIFY(A,B) (A)
#else
@@ -1362,6 +1366,10 @@
     sql_perror("setuid");
     unireg_abort(1);
   }
+#ifdef __linux__
+  /* inform kernel that process is dumpable */
+  prctl(PR_SET_DUMPABLE,1,0,0,0);
+#endif /* __linux__ */
#endif

Manual of prctl

       PR_SET_DUMPABLE
              (Since Linux 2.4) Set the state of the flag determining whether core dumps are produced for this process  upon  delivery  of  a
              signal  whose  default  behaviour  is  to  produce a core dump.  (Normally this flag is set for a process by default, but it is
              cleared when a set-user-ID or set-group-ID program is executed and also by various system calls that  manipulate  process  UIDs
              and  GIDs).  In kernels up to and including 2.6.12, arg2 must be either 0 (process is not dumpable) or 1 (process is dumpable).
              Since kernel 2.6.13, the value 2 is also permitted; this causes any binary which normally would not  be  dumped  to  be  dumped
              readable by root only.  (See also the description of /proc/sys/fs/suid_dumpable in proc(5).)



Ref: http://bugs.mysql.com/bug.php?id=21723
Some files about linux core dump:

/proc/sys/fs/suid_dumpable
/etc/profile
/etc/security/limits.conf
/proc/sys/kernel/core_pattern

Milo的海域 2012-05-30 15:32 发表评论

Notes for SNMP

Milo的海域 — Mon, 07 May 2012 08:57:00 GMT

1. Tutorial
http://net-snmp.sourceforge.net/wiki/index.php/Tutorials

2. Config & start agent
snmpconf

3. snmpwalk example

snmpwalk -v2c -c public 10.1.74.51

4. check MIB modules

snmptranslate -Dinit_mib .1.3 2>&1 |grep MIBDIR

5. extending MIB Module
http://net-snmp.sourceforge.net/wiki/index.php/TUT:Writing_a_MIB_Module
   a. download net-snmp src code
   b. MIB definition
   c. mib2c (in net-snmp-perl)
   d. make & make install
   e. edit snmpd conf & restart agent
   f. snmpwalk to verify

Milo的海域 2012-05-07 16:57 发表评论

A text2graph tool: Graphviz

Milo的海域 — Mon, 07 May 2012 06:47:00 GMT

Graphviz: a Text to Graph tool

Download:
http://www.graphviz.org/Download..php

Install:
http://www.graphviz.org/Download_linux_rhel.php

Document:
http://www.graphviz.org/Documentation.php

Example:

$ cat cluster.dot
digraph G {

        subgraph cluster_0 {
                style=filled;
                color=lightgrey;
                node [style=filled,color=white];
                a0 -> a1 -> a2 -> a3;
                label = "process #1";
        }

        subgraph cluster_1 {
                node [style=filled];
                b0 -> b1 -> b2 -> b3;
                label = "process #2";
                color=blue
        }
        start -> a0;
        start -> b0;
        a1 -> b3;
        b2 -> a3;
        a3 -> a0;
        a3 -> end;
        b3 -> end;

        start [shape=Mdiamond];
        end [shape=Msquare];
}

$ dot -Tpng cluster.dot -o cluster.png
$ gnome-open cluster.png

More examples:
http://www.graphviz.org/Gallery.php

Milo的海域 2012-05-07 14:47 发表评论

JSONView, a good firefox json viewer plugin

Milo的海域 — Fri, 17 Feb 2012 07:35:00 GMT

http://jsonview.com/

Milo的海域 2012-02-17 15:35 发表评论