沙盒：修订间差异

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{| style="border: none" width="100%"
3.1.1 Shell Operation
|-
| width="120px" | [[#Shell Operation|Shell Operation]]:
| The basic operation of the shell. 


shell的基本操作。
The following is a brief description of the shell’s operation when it reads and executes a command. Basically, the shell does the following:
|-
| [[#Quoting|Quoting]]:
| How to remove the special meaning from characters.  


如何删除字符的特殊含义。
# Reads its input from a file (see Shell Scripts), from a string supplied as an argument to the -c invocation option (see Invoking Bash), or from the user’s terminal.  
|-
# Breaks the input into words and operators, obeying the quoting rules described in Quoting. These tokens are separated by metacharacters. Alias expansion is performed by this step (see Aliases).
| [[#Comments|Comments]]:
# Parses the tokens into simple and compound commands (see Shell Commands).  
| How to specify comments.
# Performs the various shell expansions (see Shell Expansions), breaking the expanded tokens into lists of filenames (see Filename Expansion) and commands and arguments.
 
# Performs any necessary redirections (see Redirections) and removes the redirection operators and their operands from the argument list.
如何指定注释。
# Executes the command (see Executing Commands).
|}
# Optionally waits for the command to complete and collects its exit status (see Exit Status).
 
When the shell reads input, it proceeds through a sequence of operations. If the input indicates the beginning of a comment, the shell ignores the comment symbol (‘#’), and the rest of that line.  
 
当shell读取输入时，它是按照一定顺序的操作来完成的。如果输入始于一个注释，则shell将忽略改行注释符号（"#"）及其后的字符。
 
Otherwise, roughly speaking, the shell reads its input and divides the input into words and operators, employing the quoting rules to select which meanings to assign various words and characters.  
 
其他方面，大约的说，shell读取输入并且把输入内容分成字（words）和操作符（operators），通过引用规则来选各不同的种含义被指派到不同的字（words）和字符（characters）。
 
The shell then parses these tokens into commands and other constructs, removes the special meaning of certain words or characters, expands others, redirects input and output as needed, executes the specified command, waits for the command’s exit status, and makes that exit status available for further inspection or processing.
 
然后shell解析这些令牌（tokens）为命令和其他结构，之后移除某些字或字符的特殊意义，其他扩展也包括：根据需要重定向输入和输出，执行指定的指令，等待命令的退出状态，并且让合格退出状态对于其他检查和处理是可用的。

2016年6月28日 (二) 17:49的版本

3.1.1 Shell Operation

The following is a brief description of the shell’s operation when it reads and executes a command. Basically, the shell does the following:

  1. Reads its input from a file (see Shell Scripts), from a string supplied as an argument to the -c invocation option (see Invoking Bash), or from the user’s terminal.
  2. Breaks the input into words and operators, obeying the quoting rules described in Quoting. These tokens are separated by metacharacters. Alias expansion is performed by this step (see Aliases).
  3. Parses the tokens into simple and compound commands (see Shell Commands).
  4. Performs the various shell expansions (see Shell Expansions), breaking the expanded tokens into lists of filenames (see Filename Expansion) and commands and arguments.
  5. Performs any necessary redirections (see Redirections) and removes the redirection operators and their operands from the argument list.
  6. Executes the command (see Executing Commands).
  7. Optionally waits for the command to complete and collects its exit status (see Exit Status).
取自“https://wiki.ubuntu.org.cn/index.php?title=沙盒&oldid=154587”