Linux 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.

[email protected] ~]$ who | Cut-d '-f1 | Uniqrootsihua

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

[[Email protected] ~]$ W | Tail-1 | awk ' {print '} ' | iduid=500 (Sihua) gid=500 (Sihua) groups=500 (Sihua)

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

[Email protected] ~]$ CAT/ETC/PASSWD | Cut-d:-f7 | Sort | uniq-c | Sort-t '-k1-n | tail-1| awk ' {print $} '/sbin/nologin

4, the third field in the/etc/passwd the value of the largest 10 users of the information is changed to uppercase and saved to the/tmp/maxusers.txt file.

[Email protected] ~]$ sort-t:-k3-n-r/etc/passwd | head-10 | Tr ' A-Z ' A-Z ' | Tee/tmp/maxuser.txtnfsnobody:x:4294967294:4294967294:anonymous NFS user:/var/lib/nfs:/sbin/nologinsihua:x : 500:500::/home/sihua:/bin/bashavahi-autoipd:x:100:101:avahi-autoipd:/var/lib/avahi-autoipd:/sbin/ Nologinnobody:x:99:99:nobody:/:/sbin/nologinhsqldb:x:96:96::/var/lib/hsqldb:/sbin/nologindbus:x:81:81:system MESSAGE bus:/:/sbin/nologinpcap:x:77:77::/var/arpwatch:/sbin/nologinsshd:x:74:74:privilege-separated SSH:/VAR/ Empty/sshd:/sbin/nologinavahi:x:70:70:avahi daemon:/:/sbin/nologinvcsa:x:69:69:virtual CONSOLE MEMORY OWNER:/DEV:/ Sbin/nologin

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

centos6.x and previous [[email protected] ~]# Ifconfig | grep ' inet\b ' | awk ' {print $} ' | Cut-d:-f2192.168.1.67127.0.0.1centos7.x[[email protected] ~]# ifconfig | grep ' inet\b ' | awk ' {print $} ' 172.17.0.1192.168.1.63127.0.0.1192.168.122.1

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.

[[email protected] ~]# ls /etc/*.conf | tr   ' A-Z '   ' A-Z '  | tee  /tmp/etc.conf/etc/autofs_ldap_auth. Conf/etc/capi. Conf/etc/cdrecord. Conf/etc/conman. CONF/ETC/DHCP6C. CONF/ETC/DNSMASQ. Conf/etc/esd. Conf/etc/gpm-root. Conf/etc/grub. Conf/etc/gssapi_mech. Conf/etc/host. CONF/ETC/IDMAPD. Conf/etc/initlog. Conf/etc/jwhois. Conf/etc/krb5. Conf/etc/ldap. Conf/etc/ld. So. Conf/etc/lftp. Conf/etc/libaudit. Conf/etc/libuser. Conf/etc/logrotate. Conf/etc/mke2fs. Conf/etc/modprobe. Conf/etc/mtools. Conf/etc/multipath. Conf/etc/nscd. Conf/etc/nsswitch. CONF/ETC/NTP. CONF/ETC/ODDJOBD. CONF/ETC/PAM_SMB. Conf/etc/prelink. Conf/etc/reader. Conf/etc/resolv. Conf/etc/scrollkeeper. Conf/etc/sestatus. Conf/etc/smartd. Conf/etc/sysctl. Conf/etc/syslog. Conf/etc/updatedb. Conf/etc/warnquota. Conf/etc/wvdial. Conf/etc/yp. Conf/etc/yum. CONF 

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

[Email protected] ~]$ ls/var/| Wc-l20

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

[Email protected] ~]# sort-t:-k3-n/etc/group | head-10 | Cut-d:-f1rootbindaemonsysadmttydisklpmemkmem

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.

[[email protected] ~]# cat /etc/{fstab,issue} | tee /tmp/etc.testlabel=/                  /                         ext3    defaults        1  1LABEL=/boot             /boot                     ext3    defaults        1 2tmpfs                    /dev/shm                 tmpfs    defaults        0 0devpts                   /dev/pts                 devpts  gid=5,mode=620  0 0sysfs                     /sys                     sysfs   defaults        0  0proc                     /proc                    proc    defaults         0 0label=swap-sda2         swap                     swap    defaults         0 0CentOS release 5.3  (Final) kernel \ R on an \m

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

There are 4 groups of Linux users associated with the configuration file:

/ETC/PASSWD: Saving users and their property information

Meaning of each field Root:x:0:0:root:/root:/bin/bash user name: Password dot: uid:gid: Comment Information: Home directory: User default Shell

/etc/group: Group and its attribute information

What each field means: Root:x:0:root group name: group password dot: GID: comma-delimited list of users belonging to this group

/etc/shadow: User passwords and their associated properties

The meaning of each field: Root:$1$mq0q9ij0$mjtq5cavkibpd5pvbflnp0:16521:0:99999:7::: Username: encrypted Password: the date of the most recent password change: Minimum password Age: Maximum password Age: Password Disable period: Account expiration Date: Reserved field

/etc/gshadow: group password and its related properties

User and group-related administrative commands:

Useradd: Create User

-U: Specify uid-g: Specify gid-c: User's comment-d: Specify user's home directory-S: Specify user's default shell program-G: Specify user's additional group-r: Create System User

Groupadd: Creating Groups

-G: Indicates GID

-R: Creating a System Group

Usermod: User Property modification

-U: New UID

-G: New GID

-G: The new Add-on group, the original additional group will be overwritten, if the original, you want to use the-a option, indicating append

-S: New default shell

-C: New annotation information

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

-L: New name

-L: Lock the specified user

-U: Unlock the specified user

passwd: Change Password

--stdin: Don't change passwords interactively

Userdel: Deleting users

-r: Delete User home directory

Groupmod: Group Property Modification

-N: New group name

-G: New GID

Groupdel: Group Delete

GPASSWD: Group Password

-A User: Add user to the specified group

-D User: Removes additional groups of users with the current group as the group name

-A User1,user2,... : Set up a list of users with administrative rights

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

[Email protected] ~]# groupadd-g distro

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

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

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

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

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

[Email protected] ~]# echo mageedu | passwd--stdin mageiachanging password for user Mageia.passwd:all authentication tokens updated successfully.

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

[Email protected] ~]# Userdel Mandriva

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

[Email protected] ~]# groupadd peguin[[email protected] ~]# useradd-u 2002-g distro-g Peguin Slackware

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

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

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

[Email protected] ~]# groupadd admins[[email protected] ~]# usermod-ag 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;

[Email protected] ~]# echo slack123 | Passwd-n 3-x 180-w 3--stdin slackwareadjusting Aging data for user slackware.passwd:Success

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

[[email protected] ~]# groupadd clouds[[email protected] ~]# groupadd nova[[email protected] ~]# useradd-u 3003-g clouds -G Peguin,nova OpenStack

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

[[email protected] ~]# useradd-s/sbin/nologin-r MySQL

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

[Email protected] ~]# echo 123456 | passwd--stdin openstackchanging password for user Openstack.passwd:all authentication tokens updated successfully.

This article is from the "Chase Dream" blog, please be sure to keep this source http://387227.blog.51cto.com/377227/1796092

Linux third week