Shulou(Shulou.com)06/02 Report--

1. Boot script (commands that need to be executed, the operation is written in and the boot is completed)

/ etc/rc.local (soft link file)

Lrwxrwxrwx. 1 root root 13 May 27 14:43 / etc/rc.local-> rc.d/rc.local (source file)

User classification id=0 root user

Id=1-999 system zombie user

Id=1000+ ordinary user

The user information file and password file are:

/ etc/passwd

/ etc/shadow

The group information file and the group password file are:

/ etc/group

/ etc/gshadow

Content details of user information file:

User name: password: uid:gid: description: home directory: log in to shell

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

Bin:x:1:1:bin:/bin:/sbin/nologin

Daemon:x:2:2:daemon:/sbin:/sbin/nologin

Adm:x:3:4:adm:/var/adm:/sbin/nologin

Lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin

Sync:x:5:0:sync:/sbin:/bin/sync

Shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown

Halt:x:7:0:halt:/sbin:/sbin/halt

Mail:x:8:12:mail:/var/spool/mail:/sbin/nologin

Operator:x:11:0:operator:/root:/sbin/nologin

Games:x:12:100:games:/usr/games:/sbin/nologin

Ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin

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

Systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin

Dbus:x:81:81:System message bus:/:/sbin/nologin

Polkitd:x:999:998:User for polkitd:/:/sbin/nologin

Tss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin

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

Sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin

Postfix:x:89:89::/var/spool/postfix:/sbin/nologin

Chrony:x:998:996::/var/lib/chrony:/sbin/nologin

Tom:x:1000:1000:tom:/home/tom:/bin/bash

Jok:x:1001:1001::/home/jok:/bin/bash

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

Stu01:x:1002:1002::/home/stu01:/bin/bash

Alex999:x:888:1012::/home/alex999:/sbin/nologin

When this happens, there is a problem with the environment variable in the user's home directory. Just copy a copy of the environment variable to him (at this time, the system supports ordinary users to copy root users' files.

The directory is / etc/skel/.bash* these environment variables

2, create a user

Useradd user name

-u specifies the uid number

-s specifies login shell

-M does not create a home directory

-g specify the group to which the user belongs

Delete user

Userdel user name

-R recursively modify the permissions of directory files under the directory

Modify user

Usermod

-u specifies the uid number

-s specifies login shell

-G specifies the group to which the user belongs

Chown modifies the owner of a file or directory

-R recursively modify the permissions of directory files under the directory

Chown username directory / file name

Chgrp modifies the group to which a file or directory belongs

Chgrp group name directory / file name

Permission for chmod to modify a file or directory

Chmod ugo+x file name

Chmod 777 filename

Modify the password

Passwd user name

Echo '123456' | passwd-- stdin username is free to set password for each other

3, create a group

Groupadd group name

Delete a group

Groupdel group name

Modify and reorganize

Groupmod

-g reorganize id

4, expand:

Free-h View memory

Uptime View system load

Ps-aux to view system processes

Ps-ef to view system processes

Netstat views the current listening port

Top

Htop enhanced top

Iotop to view the iUnip O occupied by each process

Iftop to view system traffic

Dstat omni-directional system monitoring tool

Which user does last check and when? Which ip? When do I log in? When will you quit?

Lastlog to view the last login time of all system users

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.