Shell替换流程图

lili00681

这几天又回顾了下shell的替换流程。
这是那张Learning the korn shell的图。


这是我根据论坛上bash4.0参考文档和上图绘制的。


大家看看，有什么问题，说说意见，看法~~~

runintostar

沙发，不明觉厉的样子

lili00681

木有..因为原来在shell替换这块，踩过好几次坑，然后当时详细看了下替换的流程。今天又看到了这块，就用自己理解画了一下。回复 2# runintostar


   

runintostar

回复 3# lili00681

opening keyword的意思应该就是说是可用的关键字吧?打开关键字是什么意思？

Shell_HAT

bash解释执行顺序的流程图 中文版
http://bbs.chinaunix.net/thread-1772129-1-1.html

bash解释执行顺序的流程图 英文版
http://bbs.chinaunix.net/thread-705982-1-1.html

lili00681

喔~~~灰常感谢~~回复 5# Shell_HAT


   

lili00681

这块我也不太好理解，我觉得应该是检测一些存在的关键字的意思。回复 4# runintostar


   

Shell_HAT

回复 7# lili00681


1. Splits the command into tokens that are separated by the fixed set of metacharacters: SPACE, TAB, NEWLINE, ;, (, ), <, >, |, and &. Types of tokens include words, keywords, I/O redirectors, and semicolons.

2. Checks the first token of each command to see if it is a keyword with no quotes or backslashes. If it’s an opening keyword, such as if and other control-structure openers, function, {, or (, then the command is actually a compound command. The shell sets things up internally for the compound command, reads the next command, and starts the process again. If the keyword isn’t a compound command opener (e.g., is a control-structure "middle" like then, else, or do, an "end" like fi or done, or a logical operator), the shell signals a syntax error.

3. Checks the first word of each command against the list of aliases. If a match is found, it substitutes the alias’s definition and goes back to Step 1; otherwise, it goes on to Step 4. This scheme allows recursive aliases (see Chapter 3). It also allows aliases for keywords to be defined, e.g., alias aslongas=while or alias procedure=function.

@runintostar

844097977

这是用什么软件画的啊

Shell_HAT

回复 9# 844097977


    很多软件都可以，比如Viso