lastlog - examine lastlog file
lastlog [options]
lastlog formats and prints the contents of the last login log /var/log/lastlog file. The login-name, port, and last login time will be printed. The default (no flags) causes lastlog entries to be printed, sorted by their order in /etc/passwd.
The options which apply to the lastlog command are:
The -t flag overrides the use of -u.
If the user has never logged in the message ** Never logged in** will be displayed instead of the port and time.
The lastlog file is a database which contains info on the last login of each user. You should not rotate it. It is a sparse file, so its size on the disk is much smaller than the one shown by “ls -l” (which can indicate a really big file if you have a high UID). You can display its real size with “ls -s".
/var/log/lastlog
lastlog logging file
Large gaps in UID numbers will cause the lastlog program to run longer with no output to the screen (i.e. if mmdf=800 and last UID=170, program will appear to hang as it processes UID 171-799).