Linux learning (that's what Linux should learn) 4

• Super Admin Root

  Root is just a name, and the real super User is the UID value. Each user has a unique UID value. Root has a UID value of 0

  Uid1-999 is a different user running the system service and cannot log on to the system by default. After the UID1000 is the individual ordinary user

• User name and UID storage file in/etc/passwd, password in/etc/shadow

• GID is a group, each user has a basic group, and the added group is an extension group. GID in/etc/group

• Permissions and attribution of files

  650) this.width=650; "Width=" "height=" 102 "title=" _20170220150105.png "style=" width:500px;height:102px; "alt=" Wkiom1iqlf3ti4_1aacx7tm3s4o199.png "src=" https://s5.51cto.com/wyfs02/M01/8D/C7/wKiom1iqlF3Ti4_ 1aacx7tm3s4o199.png "border=" 0 "vspace=" 0 "hspace=" 0 "/>

  650) this.width=650; "title=" _20170220163815.png "src=" https://s2.51cto.com/wyfs02/M01/8D/C6/ Wkiol1iqqycchpoyaabygdz2ljm543.png "alt=" Wkiol1iqqycchpoyaabygdz2ljm543.png "/>

• Special permissions

  Sbit can only manage their own data, cannot delete other people's data (only in the directory) directory permissions with T,

  650) this.width=650; "title=" _20170220165758.png "src=" https://s4.51cto.com/wyfs02/M01/8D/C9/ Wkiom1iqr7vqctugaabviyoeotm635.png "alt=" Wkiom1iqr7vqctugaabviyoeotm635.png "/>

  There are also suid SGID. As the name implies, one allows the performer to temporarily own the user's permissions, one is to let the performer temporarily own the group's permissions,
  

  
  

Linux learning (that's what Linux should learn) 4