last, lastb - show a listing of last logged in users
last [options] [username...] [tty...]
lastb [options] [username...] [tty...]
last searches back through the /var/log/wtmp file (or the file designated by the -f option) and displays a list of all users logged in (and out) since that file was created. One or more usernames and/or ttys can be given, in which case last will show only the entries matching those arguments. Names of ttys can be abbreviated, thus last 0 is the same as last tty0.
When catching a SIGINT signal (generated by the interrupt key, usually control-C) or a SIGQUIT signal, 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 the reboots since the log file was created.
lastb is the same as last, except that by default it shows a log of the /var/log/btmp file, which contains all the bad login attempts.
-f, --file file
-number; -n, --limit number
-p, --present time
-s, --since time
-t, --until time
The options that take the time argument understand the following formats:
|YYYY-MM-DD hh:mm||(seconds will be set to 00)|
|YYYY-MM-DD||(time will be set to 00:00:00)|
|hh:mm:ss||(date will be set to today)|
|hh:mm||(date will be set to today, seconds to 00)|
|yesterday||(time is set to 00:00:00)|
|today||(time is set to 00:00:00)|
|tomorrow||(time is set to 00:00:00)|
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).
An empty entry is a valid type of wtmp entry. It means that an empty file or file with zeros is not interpreted as an error.
The utmp file format uses fixed sizes of strings, which means that very long strings are impossible to store in the file and impossible to display by last. The usual limits are 32 bytes for a user and line name and 256 bytes for a hostname.
Miquel van Smoorenburg <email@example.com>
For bug reports, use the issue tracker at https://github.com/util-linux/util-linux/issues.
The last command is part of the util-linux package which can be downloaded from Linux Kernel Archive https://www.kernel.org/pub/linux/utils/util-linux/.