第二次作业

1、列出当前系统上所有已经登录的用户的用户名，注意：同一个用户登录多次，则只显示一次即可。

# w

15:53:27 up 55 min,  4 users,  load average: 0.21, 0.19, 0.12

USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT

root     tty1     :0               15:06   54:43  10.65s 10.65s /usr/bin/Xorg :0 -br -verbose -audit 4 -auth /var/run/gdm/auth-for-g

root     pts/1    192.168.1.102    15:35    0.00s  0.21s  0.01s w

root     pts/2    192.168.1.102    15:44   51.00s  0.18s  0.18s -bash

user1    pts/0    192.168.1.102    15:52   29.00s  0.08s  0.08s -bash

2、取出当前系统上被用户当作其默认shell的最多的那个shell。

# cat /etc/passwd

root:x:0:0:root:/root:/bin/bash

bin:x:1:1:bin:/bin:/sbin/nologin

daemon:x:2:2:daemon:/sbin:/sbin/nologin

adm:x:3:4:adm:/var/adm:/sbin/nologin

lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin

sync:x:5:0:sync:/sbin:/bin/sync

shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown

halt:x:7:0:halt:/sbin:/sbin/halt

mail:x:8:12:mail:/var/spool/mail:/sbin/nologin

uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin

operator:x:11:0:operator:/root:/sbin/nologin

games:x:12:100:games:/usr/games:/sbin/nologin

gopher:x:13:30:gopher:/var/gopher:/sbin/nologin

ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin

nobody:x:99:99:Nobody:/:/sbin/nologin

dbus:x:81:81:System message bus:/:/sbin/nologin

usbmuxd:x:113:113:usbmuxd user:/:/sbin/nologin

vcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologin

rpc:x:32:32:Rpcbind Daemon:/var/cache/rpcbind:/sbin/nologin

rtkit:x:499:497:RealtimeKit:/proc:/sbin/nologin

avahi-autoipd:x:170:170:Avahi IPv4LL Stack:/var/lib/avahi-autoipd:/sbin/nologin

abrt:x:173:173::/etc/abrt:/sbin/nologin

rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin

nfsnobody:x:65534:65534:Anonymous NFS User:/var/lib/nfs:/sbin/nologin

haldaemon:x:68:68:HAL daemon:/:/sbin/nologin

gdm:x:42:42::/var/lib/gdm:/sbin/nologin

ntp:x:38:38::/etc/ntp:/sbin/nologin

apache:x:48:48:Apache:/var/www:/sbin/nologin

saslauth:x:498:76:Saslauthd user:/var/empty/saslauth:/sbin/nologin

postfix:x:89:89::/var/spool/postfix:/sbin/nologin

pulse:x:497:496:PulseAudio System Daemon:/var/run/pulse:/sbin/nologin

sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin

tcpdump:x:72:72::/:/sbin/nologin

user1:x:500:500::/home/user1:/bin/bash

# cut -d‘:‘ -f7  /etc/passwd | uniq -c | head -6 | tail -1

25 /sbin/nologin

3、将/etc/passwd中的第三个字段数值最大的后10个用户的信息全部改为大写后保存至/tmp/maxusers.txt文件中。

# cat /etc/passwd | sort -n -t ‘:‘ -k 3 | tail -10 | tr ‘[[:lower:]]‘ ‘[[:upper:]]‘ > /tmp/maxusers.txt

# cat /tmp/maxusers.txt

POSTFIX:X:89:89::/VAR/SPOOL/POSTFIX:/SBIN/NOLOGIN

NOBODY:X:99:99:NOBODY:/:/SBIN/NOLOGIN

USBMUXD:X:113:113:USBMUXD USER:/:/SBIN/NOLOGIN

AVAHI-AUTOIPD:X:170:170:AVAHI IPV4LL STACK:/VAR/LIB/AVAHI-AUTOIPD:/SBIN/NOLOGIN

ABRT:X:173:173::/ETC/ABRT:/SBIN/NOLOGIN

PULSE:X:497:496:PULSEAUDIO SYSTEM DAEMON:/VAR/RUN/PULSE:/SBIN/NOLOGIN

SASLAUTH:X:498:76:SASLAUTHD USER:/VAR/EMPTY/SASLAUTH:/SBIN/NOLOGIN

RTKIT:X:499:497:REALTIMEKIT:/PROC:/SBIN/NOLOGIN

USER1:X:500:500::/HOME/USER1:/BIN/BASH

NFSNOBODY:X:65534:65534:ANONYMOUS NFS USER:/VAR/LIB/NFS:/SBIN/NOLOGIN

4、取出当前主机的IP地址，提示：对ifconfig命令的结果进行切分。

# ifconfig | cut -d‘:‘ -f2 | cut -d‘ ‘ -f1 | head -2 | tail -1

192.168.1.104

5、显示/var目录下一级子目录或文件的总个数。

# ls /var/ | wc -w

21

6、取出/etc/group文件中第三个字段数值最小的10个组的名字。

# cat /etc/group | sort -t‘:‘ -k3 -n -r | tail -10

kmem:x:9:

mem:x:8:

lp:x:7:daemon

disk:x:6:

tty:x:5:

adm:x:4:adm,daemon

sys:x:3:bin,adm

daemon:x:2:bin,daemon

bin:x:1:bin,daemon

root:x:0:

7、将/etc/fstab和/etc/issue文件的内容合并为同一个内容后保存至/tmp/etc.test文件中。

# cat /etc/fstab /etc/issue >> /tmp/etc.test

# cat /tmp/etc.test

#

# /etc/fstab

# Created by anaconda on Sat Dec 10 11:22:35 2016

#

# Accessible filesystems, by reference, are maintained under ‘/dev/disk‘

# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info

#

/dev/mapper/Vol0-root   /                       ext4    defaults        1 1

UUID=f1c83d1c-a6d6-4bda-b24a-a8aba4593462 /boot                   ext4    defaults        1 2

/dev/mapper/Vol0-usr    /usr                    ext4    defaults        1 2

/dev/mapper/Vol0-swap   swap                    swap    defaults        0 0

tmpfs                   /dev/shm                tmpfs   defaults        0 0

devpts                  /dev/pts                devpts  gid=5,mode=620  0 0

sysfs                   /sys                    sysfs   defaults        0 0

proc                    /proc                   proc    defaults        0 0

CentOS release 6.6 (Final)

Kernel \r on an \m

8、请总结描述用户和组管理类命令的使用方法并完成以下练习：

(1)、创建组distro，其GID为2016；

# groupadd -g 2016 distro

# cat /etc/group | tail -1

distro:x:2016:

(2)、创建用户mandriva, 其ID号为1005；基本组为distro；

# useradd -u 1005 -g distro mandriva

# cat /etc/passwd | tail -1

mandriva:x:1005:2016::/home/mandriva:/bin/bash

(3)、创建用户mageia，其ID号为1100，家目录为/home/linux;

# useradd -u 1100 -d /home/linux mageia

# cat /etc/passwd | tail -1

mageia:x:1100:1100::/home/linux:/bin/bash

(4)、给用户mageia添加密码，密码为mageedu；

# passwd mageia

Changing password for user mageia.

New password: 

BAD PASSWORD: it is based on a dictionary word

BAD PASSWORD: is too simple

Retype new password: 

passwd: all authentication tokens updated successfully.

# cat /etc/shadow | tail -1

mageia:$6$HPyNkPCi$ae6XG0l8gyTaMXlRY9r//j9DRbZxwUSXWVvZWtxFs6sSNwfENT/4dcjD2pSNfeHUJoqM/i2DXk7Jrz5hZuRvl1:17167:0:99999:7:::

(5)、删除mandriva，但保留其家目录；

# userdel mandriva

# ls /home/

linux  mandriva  user1

(6)、创建用户slackware，其ID号为2002，基本组为distro，附加组peguin；

# useradd -u 2002 -g distro -G peguin slackware

# cat /etc/passwd | tail -1

slackware:x:2002:2016::/home/slackware:/bin/bash

# cat /etc/group | tail -1

peguin:x:2017:slackware

(7)、修改slackware的默认shell为/bin/tcsh；

# cat /etc/passwd | tail -1

slackware:x:2002:2016::/home/slackware:/bin/bash

# usermod -s /bin/tcsh slackware 

# cat /etc/passwd | tail -1

slackware:x:2002:2016::/home/slackware:/bin/tcsh

(8)、为用户slackware新增附加组admins；

# groupadd admins

# usermod -G admins slackware

# id slackware

uid=2002(slackware) gid=2016(distro) groups=2016(distro),2017(peguin),2018(admins)

(9)、为slackware添加密码，且要求密码最短使用期限为3天，最长为180天，警告为3天；

# echo ‘12345678‘ | passwd --stdin slackware

Changing password for user slackware.

passwd: all authentication tokens updated successfully.

# passwd -n 3 -x 180 -w 3 slackware

Adjusting aging data for user slackware.

passwd: Success

(10)、添加用户openstack，其ID号为3003, 基本组为clouds，附加组为peguin和nova；

# useradd -u 3003 -g clouds openstack

# usermod -a -G peguin,nova openstack

# id openstack

uid=3003(openstack) gid=2019(clouds) groups=2019(clouds),2017(peguin),2020(nova)

(11)、添加系统用户mysql，要求其shell为/sbin/nologin；

# useradd -s /sbin/nologin mysql

# cat /etc/passwd | tail -1

mysql:x:3004:3004::/home/mysql:/sbin/nologin

(12)、使用echo命令，非交互式为openstack添加密码。

# echo ‘12345678‘ | passwd --stdin slackware

Changing password for user slackware.

passwd: all authentication tokens updated successfully.

# grep ‘openstack‘ /etc/shadow

openstack:$6$ctV2w3BX$KDX7/KSS6zP5IoHulk1nges.GGvPsTZwuV.YL7qjGVYxNCFkj4xsTveB0T0ATKFLo4PlQOGZuJIzYgu0v5QOC0:17169:0:99999:7:::

9、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 -a /etc/skel/ /home/tuser1

# chmod -R 700 /home/tuser1/

# ls -al /home/tuser1/

total 28

drwx------.  4 root root 4096 Nov 28 16:58 .

drwxr-xr-x. 18 root root 4096 Jan  3 15:33 ..

-rwx------.  1 root root   18 Oct 16  2014 .bash_logout

-rwx------.  1 root root  176 Oct 16  2014 .bash_profile

-rwx------.  1 root root  124 Oct 16  2014 .bashrc

drwx------.  2 root root 4096 Nov 12  2010 .gnome2

drwx------.  4 root root 4096 Nov 28 16:52 .mozilla

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

# grep --color=auto -i ‘^s‘ /proc/meminfo 

SwapCached:            0 kB

SwapTotal:       1048572 kB

SwapFree:        1048572 kB

Shmem:               868 kB

Slab:              95144 kB

SReclaimable:      35156 kB

SUnreclaim:        59988 kB

# grep --color=auto ‘^[Ss]‘ /proc/meminfo 

SwapCached:            0 kB

SwapTotal:       1048572 kB

SwapFree:        1048572 kB

Shmem:               868 kB

Slab:              95144 kB

SReclaimable:      35156 kB

SUnreclaim:        59988 kB

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

# grep --color=auto -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

zl:x:500:500:zl:/home/zl:/bin/bash

user1:x:501:501::/home/user1:/bin/bash

user2:x:502:502::/home/user2:/bin/bash

uesr1:x:503:503::/home/uesr1:/bin/bash

user5:x:504:504::/home/user5:/bin/bash

user6:x:1000:1000::/home/user6:/bin/bash

user7:x:1001:1001::/home/user7:/bin/bash

gentoo:x:1002:1002:Gentoo Distribution:/home/gentoo:/bin/csh

centos:x:1003:1003::/home/centos:/bin/bash

mageia:x:1100:1100::/home/linux:/bin/bash

slackware:x:2002:2016::/home/slackware:/bin/tcsh

openstack:x:3003:2019::/home/openstack:/bin/bash

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

# grep --color=auto ‘/bin/bash‘  /etc/passwd

root:x:0:0:root:/root:/bin/bash

zl:x:500:500:zl:/home/zl:/bin/bash

user1:x:501:501::/home/user1:/bin/bash

user2:x:502:502::/home/user2:/bin/bash

uesr1:x:503:503::/home/uesr1:/bin/bash

user5:x:504:504::/home/user5:/bin/bash

user6:x:1000:1000::/home/user6:/bin/bash

user7:x:1001:1001::/home/user7:/bin/bash

centos:x:1003:1003::/home/centos:/bin/bash

mageia:x:1100:1100::/home/linux:/bin/bash

openstack:x:3003:2019::/home/openstack:/bin/bash

13、找出/etc/passwd文件中的一位数或两位数；

# grep --color=auto ‘\<[[:digit:]]\{1,2\}\>‘  /etc/passwd

root:x:0:0:root:/root:/bin/bash

bin:x:1:1:bin:/bin:/sbin/nologin

daemon:x:2:2:daemon:/sbin:/sbin/nologin

adm:x:3:4:adm:/var/adm:/sbin/nologin

lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin

sync:x:5:0:sync:/sbin:/bin/sync

shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown

halt:x:7:0:halt:/sbin:/sbin/halt

mail:x:8:12:mail:/var/spool/mail:/sbin/nologin

uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin

operator:x:11:0:operator:/root:/sbin/nologin

games:x:12:100:games:/usr/games:/sbin/nologin

gopher:x:13:30:gopher:/var/gopher:/sbin/nologin

ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin

nobody:x:99:99:Nobody:/:/sbin/nologin

dbus:x:81:81:System message bus:/:/sbin/nologin

vcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologin

rpc:x:32:32:Rpcbind Daemon:/var/cache/rpcbind:/sbin/nologin

rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin

haldaemon:x:68:68:HAL daemon:/:/sbin/nologin

gdm:x:42:42::/var/lib/gdm:/sbin/nologin

ntp:x:38:38::/etc/ntp:/sbin/nologin

apache:x:48:48:Apache:/var/www:/sbin/nologin

saslauth:x:498:76:Saslauthd user:/var/empty/saslauth:/sbin/nologin

postfix:x:89:89::/var/spool/postfix:/sbin/nologin

sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin

tcpdump:x:72:72::/:/sbin/nologin

14、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 --color=auto ‘^#[[:space:]][^[:space:]]‘ /etc/rc.d/rc.sysinit 

# /etc/rc.d/rc.sysinit - run once at boot time

# Taken in part from Miquel van Smoorenburg‘s bcheckrc.

# Check SELinux status

# Print a text banner.

# Only read this once.

# Initialize hardware

# Set default affinity

# Load other user-defined modules

# Load modules (for backward compatibility with VARs)

# Configure kernel parameters

# Set the hostname.

# Sync waiting for storage.

# Device mapper & related initialization

# Start any MD RAID arrays that haven‘t been started yet

# Remount the root filesystem read-write.

# Clean up SELinux labels

# If relabeling, relabel mount points.

# Mount all other filesystems (except for NFS and /proc, which is already

# mounted). Contrary to standard usage,

# filesystems are NOT unmounted in single user mode.

# The ‘no‘ applies to all listed filesystem types. See mount(8).

# Update quotas if necessary

# Check to see if a full relabel is needed

# Initialize pseudo-random number generator

# Configure machine if necessary.

# Clean out /.

# Do we need (w|u)tmpx files? We don‘t set them up, but the sysadmin might...

# Clean up /var.

# Clean up utmp/wtmp

# Clean up various /tmp bits

# Make ICE directory

# Start up swapping.

# Set up binfmt_misc

# Boot time profiles. Yes, this should be somewhere else.

# Now that we have all of our basic modules loaded and the kernel going,

# let‘s dump the syslog ring somewhere so we can find it later

# create the crash indicator flag to warn on crashes, offer fsck with timeout

# Let rhgb know that we‘re leaving rc.sysinit

15、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 | egrep --color=auto ‘LISTEN[[:space:]]*$‘

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      

tcp        0      0 127.0.0.1:6010              0.0.0.0:*                   LISTEN      

tcp        0      0 0.0.0.0:47118               0.0.0.0:*                   LISTEN      

tcp        0      0 0.0.0.0:111                 0.0.0.0:*                   LISTEN      

tcp        0      0 :::53332                    :::*                        LISTEN      

tcp        0      0 :::22                       :::*                        LISTEN      

tcp        0      0 ::1:631                     :::*                        LISTEN      

tcp        0      0 ::1:25                      :::*                        LISTEN      

tcp        0      0 ::1:6010                    :::*                        LISTEN      

tcp        0      0 :::111                      :::*                        LISTEN  

16、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；

# grep --color=auto ‘\(^[[:alnum:]]\+\>\).*\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:3005:3005::/home/bash:/bin/bash

nologin:x:3008:3008::/home/nologin:/sbin/nologin

本文出自 “11988516” 博客，谢绝转载！

第二次作业

原文：http://11998516.blog.51cto.com/11988516/1888986