The method of using regular expressions for user Management in centos7
1. Display / etc directory, starting with a non-letter, followed by a letter and other files or directories of any length and any character
[root@centos7 etc] # touch _ di234
[root@centos7 etc] # ls / etc/ | grep ^ [^ a-zA-Z] [a-zA-Z]. *
1sdf23
_ di234
[root@centos7 etc] #
2. Copy all files or directories that begin with p and end with non-numbers under the / etc directory to the / tmp/mytest1 directory.
[root@centos7 ~] # ls / etc/ | grep ^ p.* [^ 0-9] $
Pam.d
Passwd
Passwd-
Pbm2ppa.conf
Pinforc
Pki
Plymouth
Pm
Pnm2ppa.conf
3. Convert the contents of the / etc/issue file to uppercase and save to the / tmp/issue.out file
[root@centos7 ~] # cat / etc/issue | tr'amurz 'Amurz' > / tmp/mytest1
[root@centos7 ~] # cat / tmp/mytest1
\ s
KERNEL\ R ON AN\ M
[root@centos7 ~] #
4. Summarize and describe how to use user and group management commands and complete the following exercises:
(1) create a group distro with a GID of 2019
[root@centos7 ~] # groupadd-g 2019 distro
[root@centos7 ~] # cat / etc/group | grep distro
Distro:x:2019:
[root@centos7 ~] #
(2) create user mandriva, whose ID number is 1005; the basic group is distro
[root@centos7] # useradd-u 1005-g distro mandriva
[root@centos7 ~] # id mandriva
Uid=1005 (mandriva) gid=2019 (distro) groups=2019 (distro)
[root@centos7 ~] #
(3) create user mageia, whose ID number is 1100 and home directory is / homenux
[root@centos7] # useradd-u 1100-d / homenux mageia
[root@centos7 ~] # id mageia
Uid=1100 (mageia) gid=1100 (mageia) groups=1100 (mageia)
[root@centos7 ~] #
(4) add a password to the user mageia, the password is mageedu, and set the user password to expire after 7 days.
[root@centos7 ~] # echo mageedu | passwd-x 7-- stdin mageia
[root@centos7 ~] # cat / etc/shadow | grep mageia
Mageia:!!:18320:0:7:7:::
(5) delete mandriva, but keep its home directory
[root@centos7 ~] # userdel mandriva
[root@centos7] # ls-d / home/mandriva/
/ home/mandriva/
[root@centos7 ~] #
(6) create user slackware, whose ID number is 2002, basic group is distro, and additional group peguin
[root@centos7 ~] # groupadd peguin
[root@centos7] # useradd-u 2002-g distro-G peguin slackware
[root@centos7 ~] # id slackware
Uid=2002 (slackware) gid=2019 (distro) groups=2019 (distro), 2020 (peguin)
(7) modify the default shell of slackware to / bin/tcsh
[root@centos7] # usermod-s / bin/tcsh slackware
[root@centos7 ~] # grep slackware / etc/passwd
Slackware:x:2002:2019::/home/slackware:/bin/tcsh
[root@centos7 ~] #
(8) add additional group admins for user slackware
[root@centos7 ~] # groupadd admins
[root@centos7 ~] # usermod-G admins slackware
[root@centos7 ~] # id slackware
Uid=2002 (slackware) gid=2019 (distro) groups=2019 (distro), 2021 (admins)
[root@centos7 ~] #
