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@localhost home]# chmod -R 700 tuser1/
[root@localhost home]# ls -ld tuser1/
drwx------. 2 gentoo gentoo 4096 Sep 6 16:53 tuser1/
[root@localhost home]# ls -R tuser1/
tuser1/:
test1
[root@localhost home]#
2.编辑/etc/group文件，添加组hadoop。
[root@localhost ~]# tail -1 /etc/gshadow && tail -1 /etc/group
hadoop:!::
hadoop:x:5003:3.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@localhost ~]# echo "hadoop:x:600:5004::/home/hadoop:/bin/bash" >> /etc/passwd
[root@localhost ~]# echo "hadoop:hadoop:17772:0:99999:7:::" >> /etc/shadow
[root@localhost ~]# id hadoop
uid=600(hadoop) gid=5004(hadoop) groups=5004(hadoop)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@localhost ~]# cp -r /etc/skel /home/hadoop && chown -R hadoop:hadoop -R /home/hadoop
[root@localhost ~]# ls -ld /home/hadoop/
drwxr-xr-x. 4 hadoop hadoop 4096 Sep 6 17:25 /home/hadoop/
[root@localhost ~]# chmod 700 /home/hadoop/
[root@localhost ~]# ls -ld /home/hadoop/
drwx------. 4 hadoop hadoop 4096 Sep 6 17:25 /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@localhost ~]# chown -R hadoop:hadoop /home/hadoop/
[root@localhost ~]# ls -la /home/hadoop/
total 28
drwx------. 4 hadoop hadoop 4096 Sep 6 17:25 .
drwxr-xr-x. 9 root root 4096 Sep 6 17:25 ..
-rwx------. 1 hadoop hadoop 18 Sep 6 17:25 .bash_logout
-rwx------. 1 hadoop hadoop 176 Sep 6 17:25 .bash_profile
-rwx------. 1 hadoop hadoop 124 Sep 6 17:25 .bashrc
drwx------. 2 hadoop hadoop 4096 Sep 6 17:25 .gnome2
drwx------. 4 hadoop hadoop 4096 Sep 6 17:25 .mozilla6.显示/proc/meminfo文件中以大写或小写S开头的行；用两种方式；
[root@localhost ~]# grep -i "^s" /proc/meminfo
SwapCached: 0 kB
SwapTotal: 4095992 kB
SwapFree: 4095992 kB
Shmem: 3268 kB
Slab: 111268 kB
SReclaimable: 51960 kB
SUnreclaim: 59308 kB
[root@localhost ~]# grep -E "^(s|S)" /proc/meminfo
SwapCached: 0 kB
SwapTotal: 4095992 kB
SwapFree: 4095992 kB
Shmem: 3268 kB
Slab: 111248 kB
SReclaimable: 51956 kB
SUnreclaim: 59292 kB7.显示/etc/passwd文件中其默认shell为非/sbin/nologin的用户；
[root@localhost ~]# grep -v "/sbin/nologin$" /etc/passwd
root:x:0:0:root:/root:/bin/bash
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mike:x:500:500:mike_pang:/home/mike:/bin/bash
tom:x:501:502::/home/tom:/bin/bash
bhps:x:502:503:test:/home/bhps/:/bin/bash
mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash
jerry:x:503:504::/home/jerry:/bin/bash
weblogic:x:504:505::/home/weblogic:/bin/bash
gentoo:x:505:5001::/users/gentoo:/bin/bash
hadoop:x:600:5004::/home/hadoop:/bin/bash8.显示/etc/passwd文件中其默认shell为/bin/bash的用户；
[root@localhost ~]# grep "/bin/bash$" /etc/passwd
root:x:0:0:root:/root:/bin/bash
mike:x:500:500:mike_pang:/home/mike:/bin/bash
tom:x:501:502::/home/tom:/bin/bash
bhps:x:502:503:test:/home/bhps/:/bin/bash
mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash
jerry:x:503:504::/home/jerry:/bin/bash
weblogic:x:504:505::/home/weblogic:/bin/bash
gentoo:x:505:5001::/users/gentoo:/bin/bash
hadoop:x:600:5004::/home/hadoop:/bin/bash9.找出/etc/passwd文件中的一位数或两位数；
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[root@localhost ~]# grep -E "\<[[: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
haldaemon:x:68:68:HAL daemon:/:/sbin/nologin
saslauth:x:498:76:"Saslauthd user":/var/empty/saslauth:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
ntp:x:38:38::/etc/ntp:/sbin/nologin
apache:x:48:48:Apache:/var/www:/sbin/nologin
avahi:x:70:70:Avahi mDNS/DNS-SD Stack:/var/run/avahi-daemon:/sbin/nologin
gdm:x:42:42::/var/lib/gdm:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin
mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash10.显示/boot/grub/grub.conf中以至少一个空白字符开头的行；
[root@localhost ~]# grep -E "^[[:space:]]+" /boot/grub/grub.conf
root (hd0,0)
kernel /vmlinuz-2.6.32-279.el6.x86_64 ro root=UUID=9fe4ae1b-2605-4ca5-9b8c-b557301a9fb8 rd_NO_LUKS rd_NO_LVM LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet
initrd /initramfs-2.6.32-279.el6.x86_64.img11.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@localhost ~]# grep -E "^#[[: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.sysinit12.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@localhost ~]# netstat -tan |grep -E "LISTEN[[:space:]]+$"
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN
tcp 0 0 :::22 :::* LISTEN
tcp 0 0 ::1:631 :::* LISTEN
tcp 0 0 ::1:25 :::* LISTEN 13.添加用户bash, testbash, basher, nologin (此一个用户的shell为/sbin/nologin)，而后找出当前系统上其用户名和默认shell相同的用户的信息；
[root@localhost ~]# useradd bash -s /sbin/nologin && useradd testbash -s /sbin/nologin && useradd basher -s /sbin/nologin && useradd nologin -s /sbin/nologin
[root@localhost ~]# tail -4 /etc/passwd
bash:x:601:601::/home/bash:/sbin/nologin
testbash:x:602:602::/home/testbash:/sbin/nologin
basher:x:603:603::/home/basher:/sbin/nologin
nologin:x:604:604::/home/nologin:/sbin/nologin
[root@localhost ~]# grep "/sbin/nologin$" /etc/passwd|cut -d: -f1
bin
daemon
adm
lp
mail
uucp
operator
games
gopher
ftp
nobody
dbus
usbmuxd
avahi-autoipd
vcsa
rtkit
abrt
haldaemon
saslauth
postfix
ntp
apache
avahi
pulse
gdm
sshd
tcpdump
mariadb
bash
testbash
basher
nologin