Linux 之 last 登陆信息
Linux last 命令用于显示用户最近的登录信息。
官方定义为：
last, lastb - show listing of last logged in users
通过读取/var/log/wtmp文件来获取这些信息。
语法
1 | $ last [-R] [-num] [ -n num ] [-adFiowx] [ -f file ] [ -t YYYYMMDDHHMMSS] [name...] [tty...] |
参数：
-R省略 hostname 的栏位-n展示前 num 个username展示 username 的登入讯息tty限制登入讯息包含终端机代号
一般使用方法
1 | $ last |
查看最近登陆的三个用户
1 | $ last -3 |
省略hostname
1 | $ last -3 -R |
显示最后一列显示主机IP地址
1 | $ last -n 5 -a -i |
Last searches back through the file /var/log/wtmp (or the file desig‐
nated 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, usu‐
ally 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 cre‐
ated.
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.
OPTIONS
-f file
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.
-t YYYYMMDDHHMMSS
Display the state of logins as of the specified time. This is
useful, e.g., to determine easily who was logged in at a partic‐
ular time -- specify that time with -t and look for "still
logged in".
-f file
Specifies a file to search other than /var/log/wtmp.
-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 applica‐
tions).
-w Display full user and domain names in the output.
-x Display the system shutdown entries and run level changes.
NOTES
The files wtmp and btmp might not be found. The system only logs infor‐
mation in these files if they are present. This is a local configura‐
tion 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).
FILES
/var/log/wtmp
/var/log/btmp
AUTHOR
Miquel van Smoorenburg, miquels@cistron.nl
SEE ALSO
login(1), init(8)