Linux常用命令

Posted 2020-08-10

linux常用命令介绍（2）

linux权限及命令组合使用示例

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。

~]# cp -r /etc/skel /home/tuser1 && chmod -R go= /home/tuser1

2、编辑/etc/group文件，添加组hadoop。

~]# vim /etc/group
hadoop:x:5000:

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。

~]# vim /etc/passwd
hadoop:x:5000:5000::/home/hadoop:/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。

~]# cp -r /etc/skel /home/hadoop && chmod go= /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。

~]# chown -R hadoop:hadoop /home/hadoop

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

~]# grep -i ‘^s‘ /proc/meminfo
SwapCached:            0 kB
SwapTotal:       1048572 kB
SwapFree:        1048572 kB
Shmem:              6800 kB
Slab:              68880 kB
SReclaimable:      32432 kB
SUnreclaim:        36448 kB
 
~]# cat /proc/meminfo | grep "^[sS]"
SwapCached:            0 kB
SwapTotal:       1048572 kB
SwapFree:        1048572 kB
Shmem:              6800 kB
Slab:              68880 kB
SReclaimable:      32432 kB
SUnreclaim:        36448 kB

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

~]# grep -v ‘/sbin/nologin‘ /etc/passwd
root:x:0:0:root:/root:/bin/bash
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mageia:x:1100:1100::/home/linux:/bin/bash
slackware:x:2002:2016::/home/slackware:/bin/tcsh
openstack:x:3003:3332::/home/openstack:/bin/bash
inux:x:3004:3004::/home/inux:/bin/bash
hadoop:x:5000:5000::/home/hadoop:/bin/bash

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

~]# grep ‘/bin/bash$‘ /etc/passwd
root:x:0:0:root:/root:/bin/bash
mageia:x:1100:1100::/home/linux:/bin/bash
openstack:x:3003:3332::/home/openstack:/bin/bash
inux:x:3004:3004::/home/inux:/bin/bash
hadoop:x:5000:5000::/home/hadoop:/bin/bash

9、找出/etc/passwd文件中的一位数或两位数；

~]# grep ‘\<[0-9]\{1,2\}\>‘ /etc/passwd

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

~]# grep ‘^[[:space:]]\{1,\}‘ /boot/grub/grub.conf    
    kwdjnfjnvgf    
    kdnwfgkjnerwd    
    njklwdnfwdm;l    
    192843jksdanfiweu    
    4354<F2><F4>dmkwd

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；

~]# grep ‘^#[[:space:]]\{1,\}[^[:space:]]\+‘ /etc/rc.d/rc.sysinit 
#  293489         dfqervfe        fewfrew3    fr3efv  fwvefv

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；

~]# netstat -tan |grep ‘LISTEN[[:space:]]‘
tcp        0      0 0.0.0.0:80                  0.0.0.0:*                   LISTEN      
tcp        0      0 0.0.0.0:21                  0.0.0.0:*                   LISTEN      
tcp        0      0 0.0.0.0:22                  0.0.0.0:*                   LISTEN      
tcp        0      0 127.0.0.1:25                0.0.0.0:*                   LISTEN      
tcp        0      0 0.0.0.0:3306                0.0.0.0:*                   LISTEN      
tcp        0      0 :::8080                     :::*                        LISTEN      
tcp        0      0 :::21                       :::*                        LISTEN      
tcp        0      0 :::22                       :::*                        LISTEN      
tcp        0      0 :::88                       :::*                        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；

~]# useradd bash
~]# useradd testbash
~]# useradd basher
~]# useradd nologin -s /sbin/nologin
~]# grep ‘^\([^:]\+\):.*/\1$‘ /etc/passwd
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
bash:x:5001:5001::/home/bash:/bin/bash
nologin:x:5004:5004::/home/nologin:/sbin/nologin

14、显示/proc/meminfo文件中以大写或小写S开头的行；用三种方式；

~]# grep -i ‘^s‘ /proc/meminfo

SwapCached:            0 kB

SwapTotal:       1048572 kB

SwapFree:        1048572 kB

Shmem:              6800 kB

Slab:              68880 kB

SReclaimable:      32432 kB

SUnreclaim:        36448 kB

 

~]# cat /proc/meminfo | grep "^[sS]"

SwapCached:            0 kB

SwapTotal:       1048572 kB

SwapFree:        1048572 kB

Shmem:              6800 kB

Slab:              68880 kB

SReclaimable:      32432 kB

SUnreclaim:        36448 kB

 

~]# clear

[[email protected] ~]# grep ‘^[sS]‘ /proc/meminfo

SwapCached:            0 kB

SwapTotal:       1048572 kB

SwapFree:        1048572 kB

Shmem:              6800 kB

Slab:              69020 kB

SReclaimable:      32528 kB

SUnreclaim:        36492 kB

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