欢迎大家把linux shell编程中遇到的符号做个汇总 谢谢

s970741

在shell编程中常常会遇到一些变态的符号，google查找有的也不方便，欢迎大家把linux  shell编程中遇到的符号做个汇总重复的就不要发了 谢谢  小弟抛砖引玉
例如：匹配操作符~ 相当余==
例子：awk '$1 ~/xxx/' urfile相当于 awk '$1 == "xxx"'  urfile      
解释： 将显示第1个域中 与xxx相匹配的行

ly5066113

原帖由 s970741 于 2008-6-30 11:01 发表
在shell编程中常常会遇到一些变态的符号，google查找有的也不方便，欢迎大家把linux  shell编程中遇到的符号做个汇总重复的就不要发了 谢谢  小弟抛砖引玉
例如：匹配操作符~ 相当余==
例子：awk '$1 ~/xxx/' ...

~ 和 == 不等价。

echo "123" | awk '$1 ~ /1/'
echo "123" | awk '$1 == "1"'

无声无息

匹配和等同是不同的

s970741

例子不严谨 谢谢楼上的指正了  也是给我们这些初学者做个反面教材
还有没有类似的例子老师们尽管跟帖啊  方便大家学习 谢谢

blackold

范围也太大了，这些符号太多了。

s970741

^匹配行首的字符 ls -l|grep ^d
$匹配行尾的字符  
^$这是空行
.匹配一个字符
\去掉元字符特殊含义  匹配*.bat结尾的  \*\.bat$

无声无息

把正则中列一边就好了

walkerxk

还是去看看精通正则表达式吧，不然说不清楚的。

hosuk1208

~ 是说用正则
和==不一样

r2007

abs第三章，篇幅有点长，贴了一小段，最好自己看

1. Chapter 3. Special Characters
   
2. What makes a character special? If it has a meaning beyond its literal meaning, a meta-meaning, then we refer
   
3. to it as a special character.
   
4. Special Characters Found In Scripts and Elsewhere
   
5. #
   
6. Comments. Lines beginning with a # (with the exception of #!) are comments and will not be
   
7. executed.
   
8. # This line is a comment.
   
9. Comments may also occur following the end of a command.
   
10. echo "A comment will follow." # Comment here.
    
11. # ^ Note whitespace before #
    
12. Comments may also follow whitespace at the beginning of a line.
    
13. # A tab precedes this comment.
    
14. A command may not follow a comment on the same line. There is no method of
    
15. terminating the comment, in order for "live code" to begin on the same line. Use a new
    
16. line for the next command.
    
17. Of course, an escaped # in an echo statement does not begin a comment. Likewise, a #
    
18. appears in certain parameter substitution constructs and in numerical constant
    
19. expressions.
    
20. echo "The # here does not begin a comment."
    
21. echo 'The # here does not begin a comment.'
    
22. echo The \# here does not begin a comment.
    
23. echo The # here begins a comment.
    
24. echo ${PATH#*:} # Parameter substitution, not a comment.
    
25. echo $(( 2#101011 )) # Base conversion, not a comment.
    
26. # Thanks, S.C.
    
27. The standard quoting and escape characters (" ' \) escape the #.
    
28. Certain pattern matching operations also use the #.
    
29. ;
    
30. Command separator [semicolon]. Permits putting two or more commands on the same line.
    
31. echo hello; echo there
    
32. if [ -x "$filename" ]; then # Note that "if" and "then" need separation.
    
33. # Why?
    
34. echo "File $filename exists."; cp $filename $filename.bak
    
35. else
    
36. echo "File $filename not found."; touch $filename
    
37. fi; echo "File test complete."

复制代码