last, lastb - show listing of last logged in users
last [-R] [-num] [ -n num ] [-adFiowx] [ -f file ] [ -t YYYYMMDDHHMMSS ] [name...] [tty...]
lastb [-R] [-num] [ -n num ] [ -f file ] [-adFiowx] [name...] [tty...]
Last searches back through the file /var/log/wtmp (or the file designated by the -f flag) and displays a list of all users logged in (and out) since that file was created. Names of users and tty's can be given, in which case last will show only those entries matching the arguments. Names of ttys can be abbreviated, thus last 0 is the same as last tty0.
When last catches a SIGINT signal (generated by the interrupt key, usually control-C) or a SIGQUIT signal (generated by the quit key, usually control-\), last will show how far it has searched through the file; in the case of the SIGINT signal last will then terminate.
The pseudo user reboot logs in each time the system is rebooted. Thus last reboot will show a log of all reboots since the log file was created.
Lastb is the same as last, except that by default it shows a log of the file /var/log/btmp, which contains all the bad login attempts.
Tells last to use a specific file instead of /var/log/wtmp.
-num This is a count telling last how many lines to show.
-n num The same.
Display the state of logins as of the specified time. This is useful, e.g., to determine easily who was logged in at a particular time -- specify that time with -t and look for "still logged in".
-R Suppresses the display of the hostname field.
-a Display the hostname in the last column. Useful in combination with the next flag.
-d For non-local logins, Linux stores not only the host name of the remote host but its IP number as well. This option translates the IP number back into a hostname.
-F Print full login and logout times and dates.
-i This option is like -d in that it displays the IP number of the remote host, but it displays the IP number in numbers-and-dots notation.
-o Read an old-type wtmp file (written by linux-libc5 applications).
-w Display full user and domain names in the output.
-x Display the system shutdown entries and run level changes.
The files wtmp and btmp might not be found. The system only logs information in these files if they are present. This is a local configuration issue. If you want the files to be used, they can be created with a simple touch(1) command (for example, touch /var/log/wtmp).
Miquel van Smoorenburg, email@example.com
shutdown(8), login(1), init(8)