This is the 15th day of my participation in Gwen Challenge

A, rules,

  1. Grep is used in Linux to use the re
  2. Match operator
    • \ : escape
    • . : Matches any single character
    • [123a] : Contains any of the characters
    • ^ : the beginning of a line
    • $: the end of each line
    • \

      : include this word
      \>
    • \
    [root@node01 ~]# grep -E "\<ooxx\>" grep.txt 
ooxx 12121212
1212 ooxx 1212
$ooxx
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    • | : or
    • () : Choose
    • \n: backreference
      • See case 2 below
  3. Repeat operator
    • ? : Matches 0 to 1 times
    • * : matches 0 to multiple times
    • + : matches 1 to multiple times
    • {n} : matches n times
    • {n,} : matches n to multiple times
    • {n,m} : matches n to m times
  4. Re differences in Linux
    • The difference with extended regular expressions
    \? , \+, \{, \|, \(, and \)Copy the code
    • Of course, the above can also be left out
    // Use the -e argument without \ grep -eCopy the code

Second, the case

  1. Case a
# 1. The data source
ooxx12121212ooxx
ooxx 12121212
oox 12121212
1212 ooxx 1212
oo3xx
oo4xx
ooWxx
oomxx
$ooxx
oo1234xx
ooxyzxx

#2. Contains ooXX data
[root@node01 ~]# grep "ooxx" grep.txt 
oxx12121212ooxx
ooxx 12121212
1212 ooxx 1212
$ooxx

#3. Include numbers
[root@node01 ~]# grep "[0-9]" grep.txt 
oxx12121212ooxx
ooxx 12121212
oox 12121212
1212 ooxx 1212
oo3xx
oo4xx
oo1234xx

#4. Contains the number 3 or 4
[root@node01 ~]# grep "[34]" grep.txt 
oo3xx
oo4xx
oo1234xx

#5. Contains 4-bit integers
[root@node01 ~]# grep -E "[0-9]{4}" grep.txt   
oxx12121212ooxx
ooxx 12121212
oox 12121212
1212 ooxx 1212
oo1234xx

#6. The line containing the word ooxx
[root@node01 ~]# grep "\<ooxx\>" grep.txt 
ooxx 12121212
1212 ooxx 1212
$ooxx

#7. A line containing only four digits[root@node01 ~]# grep -E "[^0-9][0-9]{4}[^0-9]" grep.txt Oo1234xx //7.2 Analyzing Data and improving [root@node01 ~]# grep -E "(^[0-9]|[^0-9][0-9])[0-9]{2}([0-9]$|[0-9][^0-9])" grep.txt 1212 OOXX 1212 OO1234xx //7.3 Grep"\ [^ \ | [0-9] [^ 0-9] [0-9] \] \ [0-9] {2 \} \ ([0-9] [^ 0-9] \ | $\ [0-9])"  grep.txt
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  1. Case 2
# 1. The data source
aaabbcaaa
aa bbc aaa
bb bbc bbb
asgodssgoodsssagodssgood
asgodssgoodsssagoodssgod
sdlkjflskdjf3slkdjfdksl
slkdjf2lskdjfkldsjl

#2. Words that begin with AAA
[root@node01 ~]# grep "\<aaa" test    
aaabbcaaa
aa bbc aaa

# 3. Aaa words
[root@node01 ~]# grep "\
      
       " test
      \>
aa bbc aaa

# 4. Find out asgodssgoodsssagodssgood//4.1 initial version [root@node01 ~]# grep .*god.*good.*god.*good.* testasgodssGoodsssagodssGood# grep ".*\(god\).*\(good\).*\1.*\2" test
asgodssgoodsssagodssgood

# 5. Find out asgodssgoodsssagoodssgod<! -- [root@node01 ~] -- [root@node01 ~]# grep ".*\(god\).*\(good\).*\2.*\1" test  
asgodssgoodsssagoodssgod
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