5.2 Creating Users and Groups Flashcards
Users|Groups
a file of seven colon-delimited fields containing basic information about users
/etc/passwd
Users|Groups
a file of four colon-delimited fields containing basic information about groups
/etc/group
Users|Groups
a file of nine colon-delimited fields containing encrypted user pws
/etc/shadow
Users|Groups
a file of four colon-delimited fields file containing encrypted group passwords
/etc/gshadow
Users|Groups
world-readable file that contains a list of users, each on a separate line
/etc/passwd
Users|Groups
File: /etc/passwd
name used when user logs into system
Username
Users|Groups
File: /etc/passwd
encrypted pw or an x if shadow pw used
Password
Users|Groups
File: /etc/passwd
ID number assigned to the user in the system
User ID (UID)
Users|Groups
File: /etc/passwd
Primary group number of the user in the system
Group ID (GID)
Users|Groups
File: /etc/passwd
optional comment field used to add extra info about the user - such as full name - and can contain multiple comma-separated entries.
GECOS
Users|Groups
File: /etc/passwd
absolute path of the user’s home directory
Home Directory
Users|Groups
File: /etc/passwd
Absolute path of the program automatically launched when the user logs into the system -
Shell
usually an interactive one like /bin/bash
Users|Groups
world-readable file that contains list of groups - each on a separate line
/etc/group
Users|Groups
file /etc/passwd
name used when the user logs into the system
Username
Users|Groups
file /etc/passwd
encrypted password or an x if shadow pw used
Password
Users|Groups
file /etc/passwd
ID number assigned to the user in the system
User ID (UID)
Users|Groups
file /etc/passwd
Primary group number of the user in the system
Group ID (GID)
Users|Groups
comma-delimited list of users belonging to the group, except those for whom this is the primary group
Member list
Users|Groups
The encrypted password of the user (if the value is !, the account is locked).
Encrypted password
Users|Groups
The date of the last password change, as number of days since 01/01/1970. A value of 0 means that the user must change the pw at the next access.
Date of last password change
Users|Groups
The minimum number of days, after a password change, which must pass before the user will
be allowed to change the password again
Minimum password age
Users|Groups
The maximum number of days that must pass before a password change is required.
Max pw age
Users|Groups
The number of days, before the password expires, during which the user is warned that the
password must be changed
PW warning period
Users|Groups
The number of days after a password expires during which the user should update the
password. After this period, if the user does not change the password, the account will be
disabled.
PW inactivity period
Users|Groups
The date, as number of days since 01/01/1970, in which the user account will be disabled. An
empty field means that the user account will never expire.
Account expiration date
Users|Groups
field reserved for future use
reserved field
Users|Groups
A comma-delimited list of the administrators of the group (they can change the password of the
group and can add or remove group members with the gpasswd command).
Group administrators
Users|Groups
useradd option
create user account with custom comments
useradd -c
Users|Groups
useradd option
create new user account with custom home directory
useradd -d
Users|Groups
useradd option
create new user account by setting specific date on which it will be disabled.
useradd -e
Users|Groups
useradd option
Create a new user account by setting the number of days after the password expires during
which the user should update the password
useradd -f
Users|Groups
useradd option
Create a new user account with a specific GID
useradd -g
Users|Groups
useradd option
create new user account by adding it to multiple secondary groups
useradd -G
Users|Groups
useradd option
Create a new user account with its home directory.
useradd -m
Users|Groups
useradd option
Create a new user account without its home directory.
useradd -M
Users|Groups
useradd option
Create a new user account with a specific login shell
useradd -s
Users|Groups
useradd option
create a new user account with a specific UID
useradd -u
Users|Groups
passwd option
delete password of a user account - thus setting an empty pw making it a passwordless ccount
passwd -d
Users|Groups
passwd option
force the user account to change the pw
passwd -e
Users|Groups
passwd option
lock the user account - encrypted pw is prefixed with an exclamation mark
passwd -l
Users|Groups
passwd option
unlock the user account and the exclamation mark is removed
passwd -u
Users|Groups
passwd option
output info about the pw status for a specific account
passwd -S
