l
login(1) | login(1) |
login_directory, login_name, and login_shell are taken from the corresponding ®elds of the passwd ®le entry (see passwd(4)).
For superuser, PATH is set to:
PATH=:/usr/sbin:/usr/bin:/sbin
In the case of a remote login, the environment variable TERM is also set to the remote user's terminal type.
The environment can be expanded or modi®ed by supplying additional arguments to login, either at execution time or when login requests the user's login name. The arguments can take either the form value or varname=value, where varname is a new or existing environment variable name and value is a value to be assigned to the variable.
An argument in the ®rst form (without an equals sign) is placed in the environment as if it were entered in the form
Ln=value
where n is a number starting at 0 that is incremented each time a new variable name is required.
An argument in the second form (with an equals sign) is placed into the environment without modi®cation.
If the variable name (Ln or varname) already appears in the environment, the new value replaces the older one.
There are two exceptions. The variables PATH and SHELL cannot be changed. This prevents users logged in with restricted shell environments from spawning secondary shells that are not restricted.
Both login and getty understand simple
If /var/adm/btmp is present, all unsuccessful login attempts are logged to that ®le. This feature is disabled if the ®le is not present. The lastb command, (see last(1)), displays a summary of bad login attempts for users with read access to btmp.
If the /etc/securetty ®le is present, login security is in effect, i.e., root is allowed to log in successfully only on the ttys listed in this ®le. Restricted ttys are listed by device name, one per line. Valid tty names are dependent on the installation. An example is
console tty01 ttya1
etc.
Note that this feature does not inhibit a normal user from using the su command (see su(1)).
If the user account is con®gured to use a Smart Card, the user password is stored in the card. This password has characteristics identical to a normal password stored on the system.
In order to login using a Smart Card account, the card must be inserted into the Smart Card reader. The user is prompted for a PIN (personal identi®cation number) instead of a password during authentication. The prompts are:
login: Enter PIN:
The password is retrieved automatically from the Smart Card when a valid PIN is entered. Therefore, it is not necessary to know the password, only the PIN.
The card is locked if an incorrect PIN is entered three consecutive times. It may be unlocked only by the card issuer.
SECURITY FEATURES
On a trusted system, login prohibits a user from logging in if any of the following is true:
∙The password for the account has expired and the user cannot successfully change the password.
∙The password lifetime for the account has passed.
∙The time between the last login and the current time exceeds the time allowed for login intervals.
Section 1−462 | − 2 − |