User Management Study Notes

User Management Study Notes/etc/passwdroot: x: 0: 0: root:/bin/bash User name: Password bit: uid: gid: Description: Home directory: shell/etc/sahdowroot: $6 $4OMuqg93 $ GJFADLnehFU2zqqc0hFP/xan /. ySlEoEvPKURf6sRmv30i4DrBPo/XXnV1hn. 1I2VnvLf1imeEcPMrfv7WGq80: 15776: 0: 99999: 7: User name: Password added: last modification time: minimum interval: maximum interval: warning time: pwconv password conversion creation User: vim/etc/passwdp2p: x: 503: 503: gogogo:/home/p2p:/bin/shmkdir-p/home/p2pchown p2p/home/p2p vim/etc/shadowp2p:: 15691 :::::: new User information is stored in this directory. You need to copy all the hidden files under/etc/skel/to the new user directory. // The new user information file is a condition file for the user. (These two files are changed based on your own needs) etc/login. defs/etc/default/useradd # vim/etc/login. defsPASS_MAX_DAYS 99999 // Maximum Password days PASS_MIN_DAYS 0 // Minimum Password days PASS_MIN_LEN 5 // Minimum Password Length PASS_WARN_AGE 7 // password warning time # vim/etc/default/useradd GROUP = 100/ /default group IDHOME =/home // default home directory INACTIVE =-1 EXPIRE = // how long the user will survive SHELL =/bin/bashSKEL =/etc/skel // new user information file CREATE_MAIL_SPOOL = yes login information/etc/motd // The information that will be logged on by the user (you can write an announcement) /etc/issue // display the kernel information of the user. The reason why the individual user can change the password is-rwsr-xr-x. 1 root 27012 Aug 21 2010/usr/bin/passwd // This is the root permission to setuid to setuidsetUID = 4 chmod u + s u-s 4755 755 setGID = 2 chmod g + s g-s 2755 6755 example: # A chmod u + s/bin/touch command is run with the setUID command to execute the operation. It is the setUID or setGID file (find /-perm-4000-o-perm-2000) * If a directory with a permission of 777 has a sticking bit, each user can create a file under this directory, but only the file owned by himself can be deleted. Example: chmod o + t 17777 is used to specify the user to belong to multiple groups d: Home Directory s: Command Interpreter shellc: Description e: example of specifying the user expiration time: useradd-u 1888-g webmin-G sys, root-d/backup-s/bin/sh-c "make p2p"-e