第八课 正则表达式

正则表达式

示例1（新建名为grep.txt文件）

ooxx12121212ooxx
ooxx 12121212
oox 12121212
1212 ooxx 1212
oo3xx
oo4xx
ooWxx
oomxx
$ooxx
oo1234xx
ooxyzxx

键入如下命令

grep    "(^[0-9]|[^0-9][0-9])[0-9]{2}([0-9][^0-9]|[0-9]$)"  grep.txt

grep -E  "^[0-9]{4}[^0-9]|[^0-9][0-9]{4}[^0-9]|[^0-9][0-9]{4}$|^[0-9]{4}$" grep.txt

示例2（新建test文件）

aaabbcaaa
aa bbc aaa
bb bbc bbb
asgodssgoodsssagodssgood
asgodssgoodsssagoodssgod
sdlkjflskdjf3slkdjfdksl
slkdjf2lskdjfkldsjl

键入如下指令

cat test 
   51  grep "a" test
   52  grep  "a{3}"  test
   53  grep  "<aaa"  test
   54  grep  "<aaa>"  test
   55  grep "b" test
   56  grep  "b{2,3}" test 
   57  clear
   58  cat test
   59  grep "god" test
   60  grep "godgood" test
   61  grep "god*good" test
   62  grep "god.*good" test
   63  grep "god.*good.*god.*good" test
   64  grep "god.*good+" test
   65  grep "(god.*good)+" test
   66  grep "(god).*good.*1" test
   67  grep "(god).*(good).*1.*2" test
   68  vi test 
   69  grep "(god).*(good).*1.*2" test
   70  grep "(god).*(good).*2.*1" test