grep

 

1. echo "background-image: url(/media/images/index/im2.jpg);"|grep -oP '(?<=url\()[^)]+'

   

    

    采用负向断言

2. echo "background-image: url(/media/images/index/im2.jpg);" | grep -oP '/.+jpg'

    

3. echo "background-image: url(/media/images/index/im2.jpg);"|grep -oP '(?<=url\().+(?=\))'

   采用前后断言
   
   

4. --text 打印二进制数据
   

    

    

    

5. -l 只打印出匹配的文件名
   

    

6. -d how to handle directories   ACTION: read     recurse     skip
   read 为默认行为
   

    

    

    

    

    

7.  过滤配置文件的有效配置

   cat server.properties | grep -v '^[[:space:]]*#' | grep -v '^$'
   grep -E -v '^$|^[[:blank:]]*#' server.properties
   grep -v '^[[:space:]]*#' | tr -s '\n'
   grep -v '^[[:space:]]*#' | sed '/^$/d'
   grep -v '^[[:space:]]*#' server.properties | awk '!/^$/ {print $0}'
   grep -v '^[[:space:]]*#' server.properties | awk 'NF {print $0}'
   grep -v '^[[:space:]]*#' server.properties | awk '{if($0!="")print $0}'

    

8. -r --recursive without dereference

   -R --dereference-recursive 搜索目录时, 会 dereference symlinks 

   ln -svnf /etc/magic magic
   grep -r Magic  # nothing
   grep -R Magic