Linux Blog Third week

1. List the user name of all logged-in users on the current system, note: The same user logged in multiple times, only once.

W.H.O. | Cut-d '-f1 | Sort-u

Sort-u Removing duplicate rows

2. Remove the information about the user who last logged in to the current system.

Last | Head-1

3. Remove the shell that is the user's default shell on the current system.

cat/etc/passwd | Cut-d ': '-f7 |sort | uniq-c | Sort |head-1

4, the information of the third field in/ETC/PASSW D with the largest number of the first 10 users is changed to uppercase and then saved to the/tmp/maxusers.txt file.

Sort-t ': '-k3-n/etc/passwd |tail-10 |tr [A-z] [a-z] >/tmp/maxusers.txt

Sort-t Specify interval

5, take out the IP address of the current host, hint: The result of ifconfig command is sliced.

Ifconfig | grep ' \<inet\> ' | head-1 | Cut-d ': '-f2 |tr-d ' bcast '

6 . List the file names of all files ending with. conf in/etc directory and convert their names to uppercase and save them to the/tmp/etc.conf file.

ls/etc/*.conf | tr [A-z] [a-z] >/tmp/etc.conf

7. Displays the total number of sub-directories or files in the/var directory.

Ls-a/var/| Wc-l

8. Remove the names of the 10 groups with the smallest number of the third field in the/etc/group file.

Sort-t ': '-k3-n/etc/group | head-10 | Cut-d ': '-f1

9, the contents of the/etc/fstab and/etc/issue files are merged into the same content and saved to the/tmp/etc.test file.

Cat/etc/{fstab,issue} >/tmp/etc.test

10. Summarize the methods used to describe the user and group management commands and complete the following exercises:

Super users: 0

Normal User: 1000-65535

System users: 1--999

Login Root----- The system reads first . Bash_profile-----. BASHRC-----/ETC/BASHRC

View the user's ID Number:

ID User name

To switch users:

su [-] User name

User Configuration file:

/etc/passwd User Configuration Files

/etc/shadow User Password

/etc/group group configuration file

/etc/gshadow Group Password

/val/spool/mail User Mail directory

User Management commands:

the Create user --useradd "Format: Useradd Options User name

-C	Describe
-D	Specify home Directory
-S	Specify Shell Environment
-U	Specify UID
-G	Specify private group, owning group
-G	Specify additional groups, subordinate groups

Group Management Command: Create a group Groupadd

-R	Create a System user
-G	Specify Giu

Modify account command     usermod     usermod  options    user name

-C	Describe
-D	Modify Home Directory
-s	modify environment
-U	Modify UID
-G	Modifying private groups, owning groups
-G	Modify additional groups, subordinate groups
-L	Lock account
-U	Unlock Account

(1), create group distro, its GID is 2016;

Groupadd-g distro

(2), create user Mandriva, whose ID number is 1005; basic group is distro;

Useradd-u 1005-g distro Mandriva

(3), create user Mageia, whose ID number is 1100, home directory is/home/linux;

Useradd-u 1100-d/home/linux Mageia

(4), to the user mageia add password, password for mageedu;

echo "Mageedu" | passwd--stdin Mageia

(5), delete Mandriva, but retain their home directory;

Userdel Mandriva

(6), create user Slackware, its ID number is 2002, the basic group is distro, additional group Peguin;

Useradd-u 2002-g distro-g Peguin Slackware

(7), modify the Slackware default shell for/BIN/TCSH;

Usermod-s/bin/tcsh Slackware

(8), add additional Group admins for user Slackware;

Usermod-a-G admins Slackware

(9), add password for Slackware, and require the minimum password age of 3 days, the maximum is 180 days, warning for 3 days;

PASSWD-N3-X180-W3 Slackware & passwd Slackware

(10), add user OpenStack, whose ID number is 3003, the basic group is clouds, the additional group is Peguin and Nova;

Useradd-u 3003-g clouds-g Peguin,nova OpenStack

(11), add the system user MySQL, request its shell for/sbin/nologin;

Useradd-s/sbin/nologin-m MySQL

(12), use the echo command, non-interactive add a password for OpenStack.

echo "PASSWORD" | passwd--stdin OpenStack

This article from "12068154" blog, declined reprint!

Linux Blog Third week