博客
关于我
Linux利用grep配合正则表达式显示非空注释行内容
阅读量:390 次
发布时间:2019-03-05

本文共 3106 字,大约阅读时间需要 10 分钟。

  • 显示 /etc/inittab 文件中以 ‘#’ 号后跟着一个或多个空白字符开头并且之后是任意个非空白字符的行
  • 查看/etc/inittab的内容
[04:16:42 rooter@C8-3-55 ~]#cat /etc/inittab# inittab is no longer used.## ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.## Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target## systemd uses 'targets' instead of runlevels. By default, there are two main targets:## multi-user.target: analogous to runlevel 3# graphical.target: analogous to runlevel 5## To view current default target, run:# systemctl get-default## To set a default target, run:# systemctl set-default TARGET.target
  • 显示#开头的注释行
[04:17:54 rooter@C8-3-55 ~]#cat /etc/inittab | grep ^## inittab is no longer used.## ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.## Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target## systemd uses 'targets' instead of runlevels. By default, there are two main targets:## multi-user.target: analogous to runlevel 3# graphical.target: analogous to runlevel 5## To view current default target, run:# systemctl get-default## To set a default target, run:# systemctl set-default TARGET.target
  • 敲错了啥都不显示
    没有加-E不支持正则表达式
[04:19:33 rooter@C8-3-55 ~]#cat /etc/inittab | grep ^#[[:blank:]]+[04:20:28 rooter@C8-3-55 ~]#cat /etc/inittab | grep '^#[[:blank:]]+'
  • 显示#开头,其后是一个或多个空格的行
[04:20:38 rooter@C8-3-55 ~]#cat /etc/inittab | grep -E '^#[[:blank:]]+'# inittab is no longer used.# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target# systemd uses 'targets' instead of runlevels. By default, there are two main targets:# multi-user.target: analogous to runlevel 3# graphical.target: analogous to runlevel 5# To view current default target, run:# systemctl get-default# To set a default target, run:# systemctl set-default TARGET.target
  • 显示#开头之后是1个或多个空格,之后是非空格的行
[04:21:06 rooter@C8-3-55 ~]#cat /etc/inittab | grep -E '^#[[:blank:]]+[^[:blank:]]+'# inittab is no longer used.# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target# systemd uses 'targets' instead of runlevels. By default, there are two main targets:# multi-user.target: analogous to runlevel 3# graphical.target: analogous to runlevel 5# To view current default target, run:# systemctl get-default# To set a default target, run:# systemctl set-default TARGET.target
  • 显示#开头,之后是一个或多个空格,然后是非空格及任意字符的行
[04:21:56 rooter@C8-3-55 ~]#cat /etc/inittab | grep -E '^#[[:blank:]]+[^[:blank:]]+.*'# inittab is no longer used.# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target# systemd uses 'targets' instead of runlevels. By default, there are two main targets:# multi-user.target: analogous to runlevel 3# graphical.target: analogous to runlevel 5# To view current default target, run:# systemctl get-default# To set a default target, run:# systemctl set-default TARGET.target

问题:

  • #号开头之后紧跟着1个以上空格的及任意字符的行,为啥把#后跟空行也过滤掉了?
    空行被过滤掉了

回答:

  • 看起来像#空行,但人家直接#$就结束了!
  • 所以用一个以上blank就把看起来像空行的过滤掉了
    假空行

转载地址:http://eqkzz.baihongyu.com/

你可能感兴趣的文章
MySQL数据库优化总结
查看>>
MySQL数据库入门看这一篇文章就够了
查看>>
Mysql数据库函数contac_函数:函数删除操作语法&使用例——《mysql 从入门到内卷再到入土》...
查看>>
mysql数据库命令备份还原
查看>>
mysql数据库基础教程
查看>>
MySQL数据库备份
查看>>
mysql数据库备份与恢复
查看>>
MySQL数据库备份实战
查看>>
Mysql数据库备份的问题:mysqldump: Got error: 1049: Unknown_无需整理
查看>>
mysql数据库如何重置密码是多少钱_MySQL数据库忘记root密码如何重置修改
查看>>
MySQL数据库安装配置与常用命令
查看>>
MySQL数据库实现主从同步数据
查看>>
mysql数据库导入导出_windows系统以及linux系统下的操作---linux工作笔记042
查看>>
mysql数据库导出导入
查看>>
MySQL数据库工具类之——DataTable批量加入MySQL数据库(Net版)
查看>>
mysql数据库常用命令
查看>>
MySQL数据库必会的增删查改操作(CRUD)
查看>>
MySQL数据库性能分析与调优实践
查看>>
mysql数据库扫盲,你真的知道什么是数据库嘛
查看>>
mysql数据库批量插入数据shell脚本实现
查看>>