用户管理和正则表达式

Posted 2020-11-10 xuluchuan

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。

[[email protected] ~]# cp -r /etc/skel /home/tuser1
[[email protected] ~]# ll -d /home/tuser1/
drwxr-xr-x 2 root root 62 Jun 3 16:47 /home/tuser1/
[[email protected] ~]# ll -a /home/tuser1/
total 12
drwxr-xr-x 2 root root 62 Jun 3 16:47 .
drwxr-xr-x. 3 root root 20 Jun 3 16:47 ..
-rw-r--r-- 1 root root 18 Jun 3 16:47 .bash_logout
-rw-r--r-- 1 root root 193 Jun 3 16:47 .bash_profile
-rw-r--r-- 1 root root 231 Jun 3 16:47 .bashrc
[[email protected] ~]# chmod g=--- -R /home/tuser1/
[[email protected] ~]# chmod o=--- -R /home/tuser1/
[[email protected] ~]# ll -d /home/tuser1/
drwx------ 2 root root 62 Jun 3 16:47 /home/tuser1/
[[email protected] ~]# ll -a /home/tuser1/
total 12
drwx------ 2 root root 62 Jun 3 16:47 .
drwxr-xr-x. 3 root root 20 Jun 3 16:47 ..
-rw------- 1 root root 18 Jun 3 16:47 .bash_logout
-rw------- 1 root root 193 Jun 3 16:47 .bash_profile
-rw------- 1 root root 231 Jun 3 16:47 .bashrc

2、编辑/etc/group文件，添加组hadoop。

[[email protected] ~]# echo "hadoop:x:1000:" >> /etc/group
[[email protected] ~]# tail -1 /etc/group
hadoop:x:1000:

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。

[[email protected] ~]# echo "hadoop:x:1000:1000:hadoop:/home/hadoop:/bin/bash" >> /etc/passwd
[[email protected] ~]# tail -1 /etc/passwd
hadoop:x:1000:1000:hadoop:/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。

[[email protected] ~]# cp -r /etc/skel /home/hadoop
[[email protected] ~]# chmod g=--- -R /home/hadoop
[[email protected] ~]# chmod o=--- -R /home/hadoop
[[email protected] ~]# ll -d /home/hadoop/
drwx------ 2 root root 62 Jun 3 17:01 /home/hadoop/
[[email protected] ~]# ll -a /home/hadoop/
total 12
drwx------ 2 root root 62 Jun 3 17:01 .
drwxr-xr-x. 4 root root 34 Jun 3 17:01 ..
-rw------- 1 root root 18 Jun 3 17:01 .bash_logout
-rw------- 1 root root 193 Jun 3 17:01 .bash_profile
-rw------- 1 root root 231 Jun 3 17:01 .bashrc

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

[[email protected] ~]# chown -R hadoop:hadoop /home/hadoop
[[email protected] ~]# ll -d /home/hadoop/
drwx------ 2 hadoop hadoop 62 Jun 3 17:01 /home/hadoop/
[[email protected] ~]# ll -a /home/hadoop/
total 12
drwx------ 2 hadoop hadoop 62 Jun 3 17:01 .
drwxr-xr-x. 4 root root 34 Jun 3 17:01 ..
-rw------- 1 hadoop hadoop 18 Jun 3 17:01 .bash_logout
-rw------- 1 hadoop hadoop 193 Jun 3 17:01 .bash_profile
-rw------- 1 hadoop hadoop 231 Jun 3 17:01 .bashrc

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

[[email protected] ~]# grep -E "^(s|S)" /proc/meminfo
SwapCached: 0 kB
SwapTotal: 1048572 kB
SwapFree: 1048572 kB
Shmem: 4400 kB
Slab: 34604 kB
SReclaimable: 23448 kB
SUnreclaim: 11156 kB
[[email protected] ~]# grep "^[sS]" /proc/meminfo
SwapCached: 0 kB
SwapTotal: 1048572 kB
SwapFree: 1048572 kB
Shmem: 4400 kB
Slab: 34604 kB
SReclaimable: 23448 kB
SUnreclaim: 11156 kB
[[email protected] ~]# grep -i "^s" /proc/meminfo
SwapCached: 0 kB
SwapTotal: 1048572 kB
SwapFree: 1048572 kB
Shmem: 4400 kB
Slab: 34604 kB
SReclaimable: 23448 kB
SUnreclaim: 11156 kB

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

[[email protected] ~]# grep -v "/sbin/nologin$" /etc/passwd | cut -d‘:‘ -f1
root
sync
shutdown
halt
hadoop

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

[[email protected] ~]# grep "/bin/bash$" /etc/passwd | cut -d‘:‘ -f1
root
hadoop

9、找出/etc/passwd文件中的一位数或两位数；

[[email protected] ~]# grep -E "\<[0-9]\>|\<[0-9]{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
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/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
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin

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

[[email protected] ~]# grep -E "^[[:space:]]+" /boot/grub/grub.conf
        root (hd0,0)
        kernel /vmlinuz-2.6.32-696.el6.x86_64 ro root=UUID=b8383511-7dd4-4ca8-97ec-aa9cf6c7891a 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-2.6.32-696.el6.x86_64.img

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；

[[email protected] ~]# 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).
# Check to see if a full relabel is needed
# Update quotas if necessary
# 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

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；

[[email protected] ~]# netstat -tan | grep "LISTEN[[:space:]]*$"
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
tcp6 0 0 :::22 :::* 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；

[[email protected] ~]# useradd bash
[[email protected] ~]# useradd testbash
[[email protected] ~]# useradd basher
[[email protected] ~]# useradd -s /sbin/nologin nologin
[[email protected] ~]# grep -E "^(\<[[: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:1001:1001::/home/bash:/bin/bash
nologin:x:1004:1004::/home/nologin:/sbin/nologin