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====== User logs ====== | ====== User logs ====== | ||
+ | |||
+ | ===== Lastlog ===== | ||
+ | |||
+ | lastlog command prints the last login times for system accounts. Login information is read from the file /var/log/lastlog. | ||
+ | |||
+ | To print the last login of all the users: | ||
+ | <cli prompt='#'> | ||
+ | # lastlog | ||
+ | </cli> | ||
+ | |||
+ | To print the records of specified days older: | ||
+ | <cli prompt='#'> | ||
+ | # lastlog -b 10 | ||
+ | # lastlog --before 10 | ||
+ | </cli> | ||
+ | |||
+ | To print the logs more recent that specified days: | ||
+ | <cli prompt='#'> | ||
+ | # lastlog -t 20 | ||
+ | # lastlog --time 20 | ||
+ | </cli> | ||
+ | |||
+ | To print the last login records of specified login: | ||
+ | <cli prompt='#'> | ||
+ | # lastlog -u mike | ||
+ | # lastlog --user mike | ||
+ | </cli> | ||
+ | |||
+ | **Why is the /var/log/lastlog file so large?** | ||
+ | |||
+ | The lastlog file is reporting to be ~1.2TB in size. This file is large since it contains information regarding the last login for all users. The UID of nfsnobody on 64 bit systems is 4294967294 or 2^32-2, with 256kB per UID. | ||
+ | |||
+ | **This file is what we call a sparse file**. A sparse file is a file that contains **unallocated blocks** or "empty space", as it implies, it does not actually take up filesystem space. | ||
+ | <cli prompt='#'> | ||
+ | [root@LIN-HREL8 ~]# du -sh /var/log/lastlog | ||
+ | 40K /var/log/lastlog | ||
+ | [root@LIN-HREL8 ~]# ls -lh /var/log/lastlog | ||
+ | -rw-rw-r--. 1 root utmp 327G Nov 21 14:06 /var/log/lastlog | ||
+ | [root@LIN-HREL8 ~]# df -h /var | ||
+ | Filesystem Size Used Avail Use% Mounted on | ||
+ | /dev/mapper/rhel-var 5.0G 2.4G 2.7G 47% /var | ||
+ | </cli> | ||
+ | |||
+ | This file can potential give problems during backup, so ignore it. | ||