linux系统用户管理与grep正则表达式的示例分析

这篇文章主要介绍了linux系统用户管理与grep正则表达式的示例分析，具有一定借鉴价值，感兴趣的朋友可以参考下，希望大家阅读完这篇文章之后大有收获，下面让小编带着大家一起了解一下。

linux系统用户管理与grep正则表达式

1、复制/etc/skel目录为/home/tuser1，要求/home/tuser1及其内部文件的属组和其它用户均没有任何访问权限。

[root@suywien ~]# cp -rpv /etc/skel/ /home/tuser1/'/etc/skel/' -> '/home/tuser1/''/etc/skel/.mozilla' -> '/home/tuser1/.mozilla''/etc/skel/.mozilla/extensions' -> '/home/tuser1/.mozilla/extensions''/etc/skel/.mozilla/plugins' -> '/home/tuser1/.mozilla/plugins''/etc/skel/.bash_logout' -> '/home/tuser1/.bash_logout''/etc/skel/.bash_profile' -> '/home/tuser1/.bash_profile''/etc/skel/.bashrc' -> '/home/tuser1/.bashrc'[root@suywien ~]# useradd tuser -d /home/tuser1/useradd: warning: the home directory already exists.Not copying any file from skel directory into it.[root@suywien ~]# chmod -R go-rwx /home/tuser1/[root@suywien ~]# ll -d /home/tuser1/drwx------ 3 root root 74 Feb 12 03:04 /home/tuser1/

2、编辑/etc/group文件，添加组hadoop。

[root@suywien ~]# vim /etc/group[root@suywien ~]# tail -1 /etc/grouphadoop:x:1029

3、手动编辑/etc/passwd文件新增一行，添加用户hadoop，其基本组ID为hadoop组的id号；其家目录为/home/hadoop。

[root@suywien ~]# vim /etc/passwd[root@suywien ~]# tail -1 /etc/passwdhadoop:x:1029:1029::/home/hodoop/:/bin/bash

4、复制/etc/skel目录为/home/hadoop，要求修改hadoop目录的属组和其它用户没有任何访问权限。

[root@suywien ~]# cp -fpv /etc/skel/ /home/hadoopcp: omitting directory '/etc/skel/'[root@suywien ~]# cp -fpvR /etc/skel/ /home/hadoop'/etc/skel/' -> '/home/hadoop''/etc/skel/.mozilla' -> '/home/hadoop/.mozilla''/etc/skel/.mozilla/extensions' -> '/home/hadoop/.mozilla/extensions''/etc/skel/.mozilla/plugins' -> '/home/hadoop/.mozilla/plugins''/etc/skel/.bash_logout' -> '/home/hadoop/.bash_logout''/etc/skel/.bash_profile' -> '/home/hadoop/.bash_profile''/etc/skel/.bashrc' -> '/home/hadoop/.bashrc'[root@suywien ~]# chmod go-rwx /home/hadoop/[root@suywien ~]# ls -ld /home/hadoop/drwx------ 3 root root 74 Feb 12 03:04 /home/hadoop/

5、修改/home/hadoop目录及其内部所有文件的属主为hadoop，属组为hadoop。

[root@suywien ~]# chown -R hadoop:hadoop /home/hadoop/[root@suywien ~]# ll -al /home/hadoop/total 16drwx------ 3 hadoop hadoop 74 Feb 12 03:04 .drwxr-xr-x. 10 root root 4096 Mar 25 10:14 ..-rw-r--r-- 1 hadoop hadoop 18 Nov 20 2015 .bash_logout-rw-r--r-- 1 hadoop hadoop 193 Nov 20 2015 .bash_profile-rw-r--r-- 1 hadoop hadoop 231 Nov 20 2015 .bashrcdrwxr-xr-x 4 hadoop hadoop 37 Feb 12 03:03 .mozilla

6、显示/proc/meminfo文件中以大写或小写S开头的行；用两种方式；

[root@suywien ~]# grep ^[S,s] /proc/meminfo  SwapCached:   0 kB SwapTotal:  2097148 kB SwapFree:  2097148 kB Shmem:    9100 kB Slab:    89476 kB SReclaimable:  53176 kB SUnreclaim:  36300 kB

[root@suywien ~]# grep -i "^s" /proc/meminfo  SwapCached:   0 kB SwapTotal:  2097148 kB SwapFree:  2097148 kB Shmem:    9100 kB

7、显示/etc/passwd文件中其默认shell为非/sbin/nologin的用户；

[root@suywien ~]# grep \/sbin\/nologin$ /etc/passwdbin:x:1:1:bin:/bin:/sbin/nologindaemon:x:2:2:daemon:/sbin:/sbin/nologinadm:x:3:4:adm:/var/adm:/sbin/nologinlp:x:4:7:lp:/var/spool/lpd:/sbin/nologinmail:x:8:12:mail:/var/spool/mail:/sbin/nologin......

8、显示/etc/passwd文件中其默认shell为/bin/bash的用户；

[root@suywien ~]# grep \/bin\/bash /etc/passwdroot:x:0:0:root:/root:/bin/bashroo:x:1000:1000:root:/home/roo:/bin/bashgentoo:x:4001:4001::/home/gentoo:/bin/bashmageia:x:1100:1100::/home/linux:/bin/bashtuser:x:4003:4003::/home/tuser1/:/bin/bashhadoop:x:1029:1029::/home/hodoop/:/bin/bash

9、找出/etc/passwd文件中的一位数或两位数；

[root@suywien ~]# grep "\<[0-9]\{2,3\}\>" /etc/passwdmail:x:8:12:mail:/var/spool/mail:/sbin/nologinoperator:x:11:0:operator:/root:/sbin/nologingames:x:12:100:games:/usr/games:/sbin/nologinftp:x:14:50:FTP User:/var/ftp:/sbin/nologin......

10、显示/boot/grub/grub.conf中以至少一个空白字符开头的行；

[root@suywien ~]# grep "^[[:space:]]\+" /boot/grub2/grub.cfg  load_env set default="${next_entry}" set next_entry= save_env next_entry set boot_once=true ......

11、显示/etc/rc.d/rc.sysinit文件中以#开头，后面跟至少一个空白字符，而后又有至少一个非空白字符的行；

[root@suywien ~]# grep "^#[[:space:]]\+[^[:space:]]\+" /etc/rc.d/rc.local # THIS FILE IS ADDED FOR COMPATIBILITY PURPOSES# It is highly advisable to create own systemd services or udev rules# to run scripts during boot instead of using this file.# In contrast to previous versions due to parallel execution during boot# this script will NOT be run after all other services.# Please note that you must run 'chmod +x /etc/rc.d/rc.local' to ensure# that this script will be executed during boot.

12、打出netstat -tan命令执行结果中以'LISTEN'，后或跟空白字符结尾的行；

[root@suywien ~]# netstat -tan | grep "LISTEN[[:space:]]*$"tcp  0  0 192.168.122.1:53  0.0.0.0:*    LISTEN  tcp  0  0 0.0.0.0:22    0.0.0.0:*    LISTEN  tcp  0  0 127.0.0.1:631   0.0.0.0:*    LISTEN  tcp  0  0 127.0.0.1:25   0.0.0.0:*    LISTEN  tcp6  0  0 :::22     :::*     LISTEN  tcp6  0  0 ::1:631     :::*     LISTEN  tcp6  0  0 ::1:25     :::*     LISTEN

13、添加用户bash, testbash, basher, nologin (此一个用户的shell为/sbin/nologin)，而后找出当前系统上其用户名和默认shell相同的用户的信息；

[root@suywien ~]# useradd bash[root@suywien ~]# useradd basher[root@suywien ~]# useradd -s /sbin/nologin nologin[root@suywien ~]# grep -E "^([^:]+\>).*\1$" /etc/passwdsync:x:5:0:sync:/sbin:/bin/syncshutdown:x:6:0:shutdown:/sbin:/sbin/shutdownhalt:x:7:0:halt:/sbin:/sbin/haltbash:x:4004:4004::/home/bash:/bin/bashnologin:x:4006:4006::/home/nologin:/sbin/nologin

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