Regular expression parsing & Awk/sed/grep Practical Example Summary document

# #正则表达式特殊字符解析

"^"	Match beginning
"$"	Match end of Line
"^$"	Match whole behavior empty, empty line grep-v "^$" print a non-empty line
"."	Represents and can only represent any one character
"*"	Repeat 0 or more characters in front of each other. such as "o*", repeat one or more O
".*"	Matches all characters. Extend: "^.*"-starts with any number of characters. ". *$"-ends with any number of characters
"\"	Let the characters that have special meanings, take off the vest, restore the prototype. For example, "\.", which means "." Only. Point itself
"[ABC]"	Matches any one of the characters in the brackets in "[]"
"[^ABC]"	Matches the contents of any character that does not contain "^", that is, the match does not contain "a" | B "|" C "Content
(1) "A\{n,m\}" (2)"a\{n,\}" (3) "a\{n\}" (4)"a\{,m\}"	(1) match the previous character, repeat n->m the content, Egrep/sed-r or grep-e can save \ Escape. The "a" character repeats N to m of the content match (2) The previous character repeats at least n times (3) repeat n times for the previous character (4) The first character repeats at most m times. Will be a repeat 0-m times content matching

# #实例1#实战准备

Mkdir-p/root/test0513/

Adjust Character set: Exportlc_all=c or echo "Exportlc_all=c" >>/etc/profile && source/etc/profile

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Grep-n "^m" Oldboy.log print lines beginning with M grep-n "m$" Oldboy.log print lines ending in M grep-n "^$" Oldboy.log print Blank lines grep-nv "^$" Oldboy . log printing of non-empty rows

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grep "." Oldboy.log prints a line that contains any character, that is, the blank line does not contain characters, and does not print grep ". *" Oldboy.log any character repeats 0-n times, that is, all print all Lines grep ". *$" Oldboy.log print with any character Ends, and repeats 0-n times, including blank lines grep "^.*" Oldboy.log printing starts with any character and repeats 0-n times, including blank lines grep "old.*y" Oldboy.log print lines with any characters between old and y grep "0*" O Ldboy.log printing contains rows that repeat 0 times to any number of times 0

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grep "[A-z]" Oldboy.log print all line grep "[^a-z]" containing lowercase letters A-Z oldboy.log print all lines that do not contain a A-Z, negative

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grep "0\{1,9\}" Oldboy.log print 0 characters repeat 1-9 times line grep "0\{3\}" Oldboy.log 0 repeats 3 times line grep "0\{,3\}" Oldboy.log 0 repeats 0-3 times row grep " 0\{4,\} "Oldboy.log 0 repetitions of more than 4 rows

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# #实例2: Remove ifconfigeno167 of the NIC IP Address

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(1) SED regular match + back reference

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(2)awk

Ifconfig eno16777736|sed-n ' 2p ' |awk ' {print $} ' ifconfig eno16777736 |awk ' nr==2{print $} '

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Regular expression parsing & Awk/sed/grep Practical Example Summary document