Linux::User Management

There are three important and essential commands:

1.      useradd: add a new user

2.      usermod: modify and existing user

3.      userdel: delete and existing user

To set a password for a user:

#passwd – use this cmd

Switches:

-l :          locks the account

-u :         unlocks the account

-S:          shows the status of the account

-e:          forces the user to change passwd on next login

Important files:

/etc/passwd:     contains account info, including passwd

/etc/shadow:    contains account and password info, but encrypted

vipw:                    use to edit the passwd file

pwck:                   use to check the integrity of the passwd file

SUID:                    sets the user id of a file/dir  – used to allow users with non-root privs to change files that require root privs.

SGUI:                   sets the group ID of a file/dir – same purpose as SUID, but for groups.

Sticky Bit:            once set, this prevents a file being deleted by users even if they have the privs to modify the file.

SUID:                                                  4                                           u+s

GUID:                                                 2                                           g+s

Sticky                                                  1                                           +t

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