Shell三剑客：正则表达式(元字符)——示例

• grep love 1.txt
• /^love/
• /love$/
• /l.ve/
• /lo*ve/
• /[Ll]ove/
• /love[a-z]/
• /love[^a-zA-Z0-9]
• /.*/
• /^$/
• /^[A-Z]..$"/
• /^[A-Z][a-z]*3[0-5]/
• /[a-z]*\."/
• /^*[A-Z][a-z][a-z]$"/
• /^*[A-Za-z]*[^,][A-Za-z]*$/
• /\<fourth\>/
• /\<f.*th\> /
• /5{2}2{3}\./
• /^[\t]*$/
• /^#/
• /^[\t]*#/
• :1,$ s/\([Oo]ccur\)ence/\1rence/?
• :1,$ s /\(square\) and \(fair\)/\2 and \1/?

[root@localhost ~]# grep "^$" 1.txt 
[root@localhost ~]# grep ".*" 1.txt 
#qian
#yoa
#huang
kai
kong
cai
[root@localhost ~]# grep "^$" 1.txt 
[root@localhost ~]# grep "[A-Z]..$" 1.txt 
[root@localhost ~]# grep "[^A-Z]..$" 1.txt 
#qian
#yoa
#huang
kai
kong
cai
duo
[root@localhost ~]# grep "^[A-Z]..$" 1.txt 
[root@localhost ~]# grep "^[A-Z][a-z]*3[0-5]" 1.txt 
[root@localhost ~]# grep "[a-z]*\." 1.txt 
l.ve
[root@localhost ~]# grep "^*[A-Z][a-z][a-z]$" 1.txt 
[root@localhost ~]# grep "^*[A-Za-z]*[^,][A-Za-z]*$" 1.txt 
[root@localhost ~]# grep "\<fourth\>" 1.txt 
[root@localhost ~]# grep \<fourth\> 1.txt 
[root@localhost ~]# grep \<f.*th\> 1.txt 
[root@localhost ~]# grep "5{2}2{3}\." 1.txt 
[root@localhost ~]# grep "^[\t]*$" 1.txt 
[root@localhost ~]# grep "^#" 1.txt 
#qian
#yoa
#huang
[root@localhost ~]# grep "^[\t]*#" 1.txt 
#qian
#yoa
#huang
:1,$ s/\([Oo]ccur\)ence/\1rence/ 
:1,$ s /\(square\) and \(fair\)/\2 and \1/ 

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