Definite's Extractor » fedora

Cannot turn off “Num Lock” in Fedora

dingyichen — Thu, 12 Apr 2012 12:21:54 +0000

What do you know, pressing Fn+F6 at ThinkPad T510 toggles “Num Lock” in Fedora!

Feature request for Google Code Issue tracker: search issue status change within a specified period

dingyichen — Tue, 20 Mar 2012 02:51:31 +0000

Just submitted a feature request for Google code to provide a search field that enable us to limit the search within a specified period.

http://code.google.com/p/support/issues/detail?id=27959

Perl glob gotcha: do not rely on glob alone to determine whether files exists

dingyichen — Fri, 16 Mar 2012 07:20:07 +0000

If you, say, writing a ‘ls’ subroutine and write down something like this:

sub ls{
    my ($pattern)=@_;
    for my $f (glob $pattern){
        print "$f\n";
    }
}

If you do

ls "*.txt"

This works, but if you

ls "index.txt"

It always shows “index.txt”, no matter whether “index.txt” exists or not.

This is actually an expected behavior. Consider typing following commands in shell.

gedit *.txt
gedit index.txt

For first one, shell passes all .txt file in current directory to gedit. For second one, shell should pass ‘index.txt’ to gedit, it’s up to gedit to determine what to do with if index.txt does not exist.

So for ‘ls’ like function, following are better:

sub ls{
    my ($pattern)=@_;
    for my $f (glob $pattern){
       if ( -e $f){
           print "$f\n";
       }
    }
}

Why currying?

dingyichen — Sun, 04 Mar 2012 14:07:34 +0000

拜讀 Jserv 的以 C 語言實做 Functional Language 的 Currying 後，又去 Wikipedia 找了找 Currying 介紹, 一開始的印象其實是：「要是只要綁參數，那用 Macro 就好了。這東西該不會是學術界的蛋頭們發明出來裝高深吧。」

後來一想，一堆人都在用，不會大家都裝高深吧。於是繼續探索，發現也有一些人和我有同樣的疑問： What is ‘Currying’?, What are the practical advantages of currying?

其中講的最清楚的，就是 What are the practical advantages of currying? 的第一個答案。

簡單的說呢，不用 currying, 要寫把多個參數值相加的函數，可能就得

add2(a,b)
add3(a,b,c)
add4(a,b.c)

有了 curry, 你只需要寫一個

(define add_c
  ((curry action) +))

用的時候可以v像這樣

add_c 2 3 4 5

當然啦，要玩 currying, 還是得程式語言本身支援比較方便。

calibre: How to convert and bind multiple html pages for kindle?

dingyichen — Thu, 23 Feb 2012 15:10:11 +0000

I tried to put dive in python 3 on my kindle. Firstly I download sample from Amazon. The book is quite cheap, but well, … I would have bought it if it’s code blocks are actually represented as text (not as graph).

Then I tried calibre. Calibre is quite easy of use, but it keep telling me that

html files should be known as “zip”
The chapters should be ordered by chapter titles alphabetically, instead of original chapter number.

Luckily, calibre does provide command line too, namely, ebook-convert. It can automatically follow the hyperlinks and append the content of referenced local html files. However, it failed to recognize html files if they don’t actually have “” tags (browsers render them fine, though). Well, inserting and on multiple files are not hard if you know sed and bash.

Are we done yet? No. option “–breadth-first” is required, otherwise the chapter order is still messed up, as the latter chapters might inserted in the front just because they are referred first.

Are we there yet ? Well, yes. But of course, there are many knobs that can be tuned if you want better result.

briss for Fedora

dingyichen — Fri, 13 Jan 2012 06:56:05 +0000

Briss is a convenient tool to crop pdf to necessary size. I have pack it as rpm for Fedora 16 (though other releases with java-1.6 are fine) and put it in http://repos.fedorapeople.org/repos/dchen/java-apps/

It’s from binary jar, as I don’t really have time to make a proper fedora package and go through the review process. It’s GPLv3, so feel free to convert it and submit to fedora.

irc.freenode.net: #fedora-unregistered

dingyichen — Wed, 21 Sep 2011 10:55:00 +0000

I was fed up that I always be redirected to #fedora-unregistered instead of #fedora, even I have already registered the nickname.

Today I found: What is the difference between NickServ Password and Server Password in X-Chat, then use Server password instead. Finally it works!

Skype for Fedora 14 x86_64

dingyichen — Fri, 22 Apr 2011 18:07:00 +0000

If you use the skype official rpm on Fedora14 x86_64, it will end up “command not found”.

Apparently it’s dependency missing in spec file, so I just install qt.i686 and qt-x11.i686.

It’s still showing:
skype: error while loading shared libraries: libXv.so.1: cannot open shared object file: No such file or directory

and

skype: error while loading shared libraries: libXss.so.1: cannot open shared object file: No such file or directory

then I installed the missing dependency:
yum install libXv.i686 libXScrnSaver.i686

Summary:
In Fedora 14 x86_64, you need
yum -y install qt.i686 qt-x11.i686 libXv.i686 libXScrnSaver.i686

cmake-fedora

dingyichen — Wed, 10 Nov 2010 13:54:00 +0000

Were you ever bored by the following release chores:

Verifying the consistence of versioning in program, tarball, git tags, RPMs, ChangeLog, and whatever place that need to know current version?
Pasting change summaries and details in submission messages, ChangeLog, RPM ChangeLog, bodhi notes, and the hosting website?
Forget to rpmlint again?
Having to scratch build, commit, build, and submitting to bodhi in for each dist you intent to support?
Embarrassed by inconsistency amongst source tarballs and RPMs?
Need to manually upload source tarball to hosting service providers?
Manually to copy the COPYING and fill the information in COPYING?

I do, thus the birth of the cmake-fedora, which automates many chores describe above.

CMake is a powerful cross-platform build system, it is considered faster and easier to understand than autotools. However, there are some gotchas for novice packagers.

For example, without setting CPACK_SOURCE_IGNORE_FILES, novices might notice the tarball grow geometrically each time they pack, because the old tarballs are not excluded.

Advance developers also benefit from these convenient macros and targets for project release chores like writing the same release information to ChangeLog, RPM spec file, source control tags, koji build and bodhi submission.

What does cmake-fedora do exactly? (Feature List)

Edit once in RELEASE-NOTES.txt, applied everywhere, such as:
- ChangeLog
- Source tarball generation
- RPM
- koji scratch build
- fedpkg scratch build, commit, build, update
- bodhi submission, the Change is applied as note.
- Uploading to hosting services like FedoraHosted, SourceForge, GitHub, Google Project hosting (the last three is under development)
A script to generate templates of build files and documents, such as
- CMakeLists.txt
- MAINTAINER_SETTING_NO_PACK
- RELEASE-NOTES.txt
- SPECS/project.spec.in
- COPYING (and COPYING.LESSER for LGPL)
Helper macros and targets to:
- Build
- Pack source tarball
- Build rpm, srpm
- rpmlint
- Submit to fedpkg, koji, and bodhi
- Clean older builds
- uninstall

Project’s home page is at here.

Shared X start-up file.

dingyichen — Wed, 06 Oct 2010 11:14:00 +0000

I used to rotate among six desktop environments/window managers. However, not all of them support XDG autostart (see IBusStartUpTroubleShooting for reference).

Fortunately, there is a place for set once, all enjoy, namely, /etc/X11/xinit/xinitrc.d/.

So put following script at that directory:

#!/bin/sh
if [ -x "$HOME/.xstart" ]; then
        source $HOME/.xstart
fi

And put whatever you like in ~/.xstart