WangLu's Notes

最近要把一个程序移植到Debian-kfreebsd上，并不如想象中的顺利。 主要是ptrace在两个平台上不太一样。 首先是宏定义，linux底下都叫PTRACE_*，freebsd上都是PT_*。这个也许不算什么 然后是ptrace函数的参数，主要是value这个，linux下面是long很好用，但是freebsd下是int，这样64位的时候就有些问题。 但是freebsd的ptrace有个更好用的操作PT_IO，可以自定义读写长度，而linux底下没有，要自己搞。 最后一个，花了我很长时间才解决的，是CONTINUE这个操作，linux下面addr这个参数是被忽略的，直接从中断的地方继续；但是freebsd下面则可以利用这个参数指定从哪里继续，如果希望从中断的地方继续，则指定为1即可。 目前只遇到这些，从这些方面来看，还是freebsd的接口更好用一些。 Recently I've been porting a software from Linux to Debian-kfreebsd, but it's not as easy as I had expected. The problem is the interface of ptrace is not exactly the same between linux and kfreebsd. The first is the names of the macros, which are PTRACE_* under linux and PT_* under freebsd. Secondly the function `ptrace' is not the same, the parameter `value' is `long' under Linux, but `int' under freebsd, so it seems that there'll be a problem on 64 bit freebsd. However, there's another operation called PT_IO under freebsd, using which we can specify the number of bytes we

原文: http://pebblesinthesand.wordpress.com/2008/05/22/a-srcipt-for-running-processes-in-parallel-in-bash/ 技巧是控制了最大并发数目，当前并发数过大时，等待有进程退出才开始下一个。 我现在正在写的脚本里正需要这个，借鉴过来 #!/bin/bash NUM=0 QUEUE="" MAX_NPROC=2 # default REPLACE_CMD=0 # no replacement by default USAGE="A simple wrapper for running processes in parallel. Usage: `basename $0` [-h] [-r] [-j nb_jobs] command arg_list -h Shows this help -r Replace asterix * in the command string with argument -j nb_jobs Set number of simultanious jobs [2] Examples: `basename $0` somecommand arg1 arg2 arg3 `basename $0` -j 3 \"somecommand -r -p\" arg1 arg2 arg3 `basename $0` -j 6 -r \"convert -scale 50% * small/small_*\" *.jpg" function queue { QUEUE="$QUEUE $1" NUM=$(($NUM+1)) } function regeneratequeue { OLDREQUEUE=$QUEUE QUEUE="" NUM=0 for PID in $OLDREQUEUE do if [ -d /proc/$PID ] ; then QUEUE="$QUEUE $PID" NUM=$(($NUM+1)) fi done } function che