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目前顯示的是 五月, 2010的文章

fork()、pipe()、dup2() 和 execlp() 的組合技法

對一般程式來說,管線(pipe)機制很少會用到,尤其對於在 Windows 底下的程式開發者來說,很可能前所未聞,而在 Unix-like 環境中常見的例子,就是往往在命令後面加上『|』,其意味使用『管子(pipe)』將內容導入另一個程式裡,如:『dmesg | grep ALSA』。在該例中,Shell 有趣的將 demsg 標準輸出(standard output)全數導入 grep 程式的標準輸入(standard input)中,再交由 grep 處理並找出存在 ALSA 字串的句子所在。

另一個情況,Web Server 在支援 CGI 時,也會使用到 pipe。這是最典型的例子,當 Web Server 欲執行一支外部 CGI Program 時,會利用 pipe 去模擬該 CGI 的標準輸入及輸出(Standard I/O)。以上說明當然只是大致上的做法,細節還需加上 fork() 和 dup2() 的配合,透過個範例可清楚瞭解這部份的實作。

這是一個簡單的範例:
void cgi_run(const char* filename) { char buffer[1024] = { 0 }; int len; int pfd[2]; int status; pid_t pid; /* create pipe */ if (pipe(pfd)<0) return -1; /* fork to execute external program or scripts */ pid = fork(); if (pid<0) { return 0; } else if (pid==0) { /* child process */ dup2(pfd[1], STDOUT_FILENO); close(pfd[0]); /* execute CGI */ execlp(filename, filename, NULL); exit(0); } else { /* parent process */ close(pfd[1]); …

SCIM Patch: Auto enable input method when getting keyboard focus for a GTK+ text entry

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As you know, Apple iPad is the latest craze and brings back tablet PC marketing cause most manufactories aim to begin to produce products with touchscreen. In order to make applications work with touchscreen for tablet PC, implementing on-screen keyboard is the major issue. There are many open source solutions you can get from internet, but you may get a question, what time is better to start the on-screen keyboard? It is a good idea that enable on-screen keyboard when input box get focus, that is just like Apple iPhone, iPod, iPad and a lot smart phone.

SCIM has panel support, it can provide on-screen keyboard. So I have patched scim-bridge to support that auto enable input method when getting keyboard focus for a GTK+ text entry. If so input method is enabled, SCIM will show on-screen keyboard automatically.

Here is my patch you can get:
http://people.linux.org.tw/~fred/patches/scim-bridge-0.4.16_client-gtk-autoshow.patch