How does Linux create new users and add groups?

1. Display / etc/ directory, starting with a non-character, followed by a letter and other files or directories of any length and any character

Use the ls command, combined with file wildcards, to find: man glob can find expressions of file wildcard symbols; [: alnum:] letters and numbers; [! [: alnum:]] non-letters and numbers; [: alpha:] uppercase and lowercase letters; * any character contains empty

2 copy all files or directories under the / etc directory that begin with p and end with non-numbers into the / tmp/mytest1 directory.

Mkdir / tmp/mytest1; cp-a / etc/p* [! [: digit:]] / tmp/mytest1

3 convert the contents of the / etc/issue file to uppercase and save to the / tmp/tr.txt file.

Tr is a standard input, output standard output software, can do conversion, do repeated character compression and deletion; can cooperate with the pipeline and > append to the file; tr [Amurz] [Amurz]

< /etc/issuecat /etc/issue | tr [a-z] [A-Z]tr [a-z] [A-Z] < /etc/issue | tee -a tr1.txtcat /etc/issue | tr [a-z] [A-Z] >

> tr2.txt

4 Please summarize and describe the usage of user and group management commands and complete the contact

Useradd userdel creates and deletes users; groupadd groupdel creates and deletes groups

4.1 create a group distro with a GID of 2019

Groupadd-g 2019 distro

4.2 create user mandriva with the ID number 1005; the basic group is distro

Useradd-u 1005-g distro mandriva

4.3.Create user mageia with ID number 1100 and home directory / home/linux

Useradd-u 1100-d / home/linux mageia

4.4 add a password to the user mageia with the password mageedu, and set the user password to expire after 7 days

Passwd-x 7 mageiaecho mageedu | passwd-stdin mageia

4.5 remove mandriva but keep its home directory

Userdel mandriva

Create a user slackware with the ID number 2002, the basic group distro, and the additional group peguin

Useradd-u 2002-g distro-G peguin slackware

4.7 modify the default shell of slackware to / bin/tcsh

Usermod-s / bin/tcsh slackware

4.8 add additional group admins for user slackware

Usermod-a-G admins slackware