The Linux command uses

1. List the user names of all logged-in users on the current system, note: The same user logged in multiple times, only one time is displayed

[email protected] ~]# who | Cut-d '-F 1 | Sort-u

Admin

Root

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

[Email protected] ~]# CAT/ETC/PASSWD | Cut-d:-F 7 | uniq-c | Sort-n | Tail-1

25/sbin/nologino

3. Change the information in the third field in the/etc/passwd to the/tmp/maxusers.txt file with the largest number of the first 10 users.

[Email protected] ~]# CAT/ETC/PASSWD | Sort-t:-K 3-n | tail-10 | TR "A-Z" "A-Z" >/tmp/maxusers.txt

[Email protected] ~]# Cat/tmp/maxusers.txt

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

Pulse:x:497:495: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

Admin:x:500:500::/home/admin:/bin/bash

User1:x:501:502::/home/user1:/bin/bash

User2:x:502:503::/home/user2:/bin/bash

Centos:x:503:504::/home/centos:/bin/bash

Root123:x:504:505::/home/root123:/bin/bash

Nfsnobody:x:65534:65534:anonymous NFS User:/var/lib/nfs:/sbin/nologin

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

[Email protected] ~]# Ifconfig | grep "\ (inet add\) | head-1 | Cut-d:-F 2 | Tr-d Bcast

192.168.10.103

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

[Email protected] ~]# Tree-l 1/var | Wc-l

24

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

[Email protected] ~]# Cat/etc/group | Sort-t:-K 3-n | head-10 | Cut-d:-F 1

Root

Bin

Daemon

Sys

cd/

Tty

Disk

Lp

Mem

Kmem

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

[Email protected] ~]# cat/etc/fstab/etc/issue >/tmp/etc.text

[Email protected] ~]# Cat/tmp/etc.text

#

#/etc/fstab

# Created by Anaconda on Fri Nov 25 05:32:50 2016

#

# Accessible filesystems, by reference, is maintained under '/dev/disk '

# See mans Pages Fstab (5), Findfs (8), mount (8) and/or Blkid (8) for more info

#

/DEV/MAPPER/VOLGROUP-LV_ROOT/EXT4 Defaults 1 1

Uuid=40cea874-31c8-404a-9463-32c09bad241c/boot EXT4 Defaults 1 2

/dev/mapper/volgroup-lv_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 6.8 (Final)

Kernel \ r on an \m

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

User created: Useradd

-u:uid, defined in/etc/login.defs

-G:GID Specifies the base group to which the user belongs, either as a group name or as a GID

-C: User's comment information

-D: The specified path is the home directory.

-S: Specifies the user's default shell program, the available list is in/etc/shells

-G: Indicates additional groups for the user.

-r: Create a System user.

Group creation: Groupadd

-G: Specify GID number

User Property Modification: Usermod

-U: New UID

-G: New Basic Group

-G: The new additional group, the original additional group will be overwritten, to retain the original, you also want to use the-a option.

-S: New shell

-C: New annotation information

-D: New home directory, files in the original home directory will not be moved to the new home directory at the same time, to move, then use the-M option

-l:login Name: The new name

-l:lock the specified user

-u:unlock the specified user

-E:YYYY-MM-DD indicates the expiration date of the user account

-F: Set the duration of inactivity

Group Property Modification: Groupmod

-N: New name

-G: New GID

User Add Password: passwd (Modify the password of the specified user, only root user rights)

passwd: Change your password

-L: Lock the specified user

-U: Unlock the specified user

-n:mindays: Specify the shortest period of use

-x:maxdays: Maximum use Period

-I: Inactivity period

--stdin: Receives the user password from the standard input.

echo "passwd" | passwd--stdin USERNAME

Group Password: gpasswd

-A: Add user to the specified group

-D: Delete the user's additional group with the current group name

-A: Set the list of users who manage permissions

Delete User: Userdel

-r: Delete User's home directory

Delete Group: Groupdel

Groupdel GROUP

Temporary Switch Base Group: NEWGRP

If the user does not belong to this group, a password is required

To modify a user's properties: chage

-D Last_day

-E,--expiredate expire_date

-I.,--inactive inactive

-M,--mindays min_days

-M,--maxdays max_days

-W,--warndays Warn_days

To view the user's related ID information: ID

-u:uid

-g:gid

-g:group

-n:name

To switch users or perform as a different user: Su

Su UserName: non-login switch

Su-username: Login switch. The target user's profile is read and completely switched.

Note:root to other users without a password, a password is required for non-root user Switching.

A different Identity execution command: su-username-c ' command '

To modify some specific information: CHFN

Modify the new Shell:chsh

Show user details: Finger

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

[Email protected] ~]# Groupadd distro-g 2016

[Email protected] ~]# Cat/etc/group | Tail-1

DISTRO:X:2016:

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

[Email protected] ~]# useradd mandriva-u 1005-g distro

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

[Email protected] ~]# useradd mageia-u 1100-d/home/linux

[[Email Protected]gon ~]# cat/etc/passwd | Tail-1

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

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

[Email protected] ~]# passwd Mageia

Changing password for user Mageia.

New Password:

Bad Password:it are based on a dictionary word

Bad Password:is too simple

Retype new Password:

Passwd:all authentication tokens updated successfully.

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

[Email protected] ~]# Userdel Mandriva

[Email protected] ~]# ls/home/

Admin CentOS Linux Mandriva root123 user1 user2

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

[Email protected] ~]# Groupadd Peguin

[Email protected] ~]# useradd slackware-u 2002-g distro-g Peguin

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

[Email protected] ~]# usermod slackware-s/bin/tcsh

[Email protected] ~]# CAT/ETC/PASSWD | Tail-1

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

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

Usermod slackware-ag Admins

[[email protected] ~]# ID Slackware

uid=2002 (Slackware) gid=2016 (distro) groups=2016 (distro), 2018 (admins)

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

[Email protected] ~]# passwd-n 3-x 180-w 3 Slackware

[Email protected] ~]# Cat/etc/shadow | Tail-1

slackware:!! : 17155:3:180:3:::

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

[Email protected] ~]# useradd openstack-u 3003-g clouds-g Peguin,nova

[[email protected] ~]# ID OpenStack

uid=3003 (OpenStack) gid=2020 (Clouds) groups=2020 (Clouds), Peguin (Nova)

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

[Email protected] ~]# useradd mysql-s/sbin/nologin

[Email protected] ~]# CAT/ETC/PASSWD | Tail-1

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

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

[Email protected] ~]# echo "11qqwww" | passwd--stdin OpenStack

Changing password for user OpenStack.

Passwd:all authentication tokens updated successfully.

9, the replication/etc/skel directory is/home/tuser1, requires/home/tuser1 and its internal files belong to the group and other users do not have any access rights.

[Email protected] ~]# cp-r/etc/skel/home/tuser1 && chmod-r go=/home/tuser1

10. Display lines in the/proc/meminfo file that begin with uppercase or lowercase s; in two ways

[Email protected] ~]# grep-i "^s"/proc/meminfo

[[email protected] ~]# grep "^[ss]"/proc/meminfo

swapcached:0 KB

swaptotal:2064380 KB

swapfree:2064380 KB

shmem:3844 KB

slab:139288 KB

sreclaimable:94680 KB

sunreclaim:44608 KB

11. Display the default shell of the/etc/passwd file as a non-/sbin/nologin user;

[Email protected] ~]# 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

Admin:x:500:500::/home/admin:/bin/bash

User1:x:501:502::/home/user1:/bin/bash

User2:x:502:503::/home/user2:/bin/bash

Centos:x:503:504::/home/centos:/bin/bash

Root123:x:504:505::/home/root123:/bin/bash

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

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

Openstack:x:3003:2020::/home/openstack:/bin/bash

12. Display the user whose default shell is/bin/bash in/etc/passwd file;

[[email protected] ~]# grep ". *\ (/bin/bash\) $"/etc/passwd

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

Admin:x:500:500::/home/admin:/bin/bash

User1:x:501:502::/home/user1:/bin/bash

User2:x:502:503::/home/user2:/bin/bash

Centos:x:503:504::/home/centos:/bin/bash

Root123:x:504:505::/home/root123:/bin/bash

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

Openstack:x:3003:2020::/home/openstack:/bin/bash

13. Find out one or two digits in the/etc/passwd file;

[Email protected] ~]# grep-o "\<[0-9]\{2,3\}\>"/etc/passwd

12

10

14

11

12

100

13

30

14

50

99

99

14, the display/etc/rc.d/rc.sysinit file with the beginning of #, followed by at least one white space character, and then have at least one non-whitespace character line;

[[email protected] ~]# grep "^#[[: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

15, the Netstat-tan command execution results in the "LISTEN", followed by or with a blank character end of the line;

[Email protected] ~]# Netstat-tan | grep ". *listen[[:space:]]\+$"

TCP 0 0 0.0.0.0:111 0.0.0.0:* LISTEN

TCP 0 0 0.0.0.0:39476 0.0.0.0:* LISTEN

TCP 0 0 0.0.0.0:22 0.0.0.0:* LISTEN

TCP 0 0 127.0.0.1:631 0.0.0.0:* LISTEN

TCP 0 0 127.0.0.1:25 0.0.0.0:* LISTEN

TCP 0 0::: 111:::* LISTEN

TCP 0 0::: 53232:::* LISTEN

16, add user bash, Testbash, basher, Nologin (this one user's shell is/sbin/nologin), and then find the current system on its user name and the default shell of the same user information;

[[email protected] ~]# grep "^\ ([[: 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

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

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

Nfsnobody:x:65534:65534:anonymous NFS User:/var/lib/nfs:/sbin/nologin

Bash:x:3005:3005::/home/bash:/bin/bash

Basher:x:3007:3007::/home/basher:/bin/bash

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

The Linux command uses