What is the lastlog file in Linux?
/var/log/lastlog
lastlog is a program available on most Linux distributions. It formats and prints the contents of the last login log file, /var/log/lastlog (which is a usually a very sparse file), including the login name, port, and last login date and time.
What is lastlog in var log?
The /var/log/lastlog file is used to store information about the successful logins to the host. On several versions of RedHat Enterprise Linux and Fedora, corruption in this file can cause the size to be misrepresented. This has no effect on the real space used by the file, as reported by the du command.
Why is lastlog so huge?
Answer. The file is a sparse file and is not actually taking up as much physical space as it shows. lastlog records the last login of each user. The large size merely shows you the potential size of the file if there were a maximum amount of users (around 2^32 users).
Can lastlog be deleted?
Task: Clear last login information by deleting /var/log/lastlog. Press CTR+D to save the changes.
What is wtmp file?
Wtmp is a file on the Linux, Solaris, and BSD operating systems that keeps a history of all logins and logouts. On Linux systems, it is located at /var/log/wtmp. Various commands access wtmp to report login statistics, including the who and lastb commands. Log, Operating system, Operating System terms.
What is sparse file Linux?
Sparse files are files that have large amounts of space preallocated to them, without occupying the entire amount from the filesystem. The term “sparse file” is used to mean one containing “holes”; it is easy to recognize one on a running system because its disk usage is less than its size.
What is maintained wtmp and UTMP files?
Unlike the system log files and the authentication log files, all of these files are binary files. utmp will give you complete picture of users logins at which terminals, logouts, system events and current status of the system, system boot time (used by uptime) etc. wtmp gives historical data of utmp.
What is BTMP file?
From Wikipedia, the free encyclopedia. utmp, wtmp, btmp and variants such as utmpx, wtmpx and btmpx are files on Unix-like systems that keep track of all logins and logouts to the system.
What is var log Faillog?
faillog displays the contents of the failure log database (/var/log/faillog). It can also set the failure counters and limits. When faillog is run without arguments, it only displays the faillog records of the users who had a login failure.
What do Lastlog and Lastb commands do?
On the Linux systems there are three standard commands that show the information about last logged in users: last , lastb , and lastlog . The output of these commands include: login-name, last login time, IP address, port etc. And sometimes, to keep anonymity, it is required to erase last login history.
What are wtmp and utmp files?
utmp will give you complete picture of users logins at which terminals, logouts, system events and current status of the system, system boot time (used by uptime) etc. wtmp gives historical data of utmp. btmp records only failed login attempts.
Can I delete wtmp file?
You can delete it. The next time somebody logs in/out the wtmp will be updated.
How often does Cron call logrotate on / var / log?
To prevent a large volume of log files from filling up the ‘/var/log’ filesystem, there is a facility called as logrotate. A daily cron job calls this logrotate into action once a day.
Which is the last command in CentOS / RHEL?
The command ‘last’ parses this data file and gives back the output. There is also a provision for another data file ‘ /var/log/btmp ‘ to be created to store bad logins, which can be read using the command ‘ lastb ‘.
How big is the lastlog partition in Red Hat?
The partition is 4G (/var/log), however ls -lh /var/log/lastlog believes it is 465GB (four hundred and sixty-five GB). However, a df -PhT /var/log shows only 65M (sixty-five MB) being actually used.
How big is the lastlog backup file size?
If your backup utility/methodology isn’t sparesfile-aware, you’ll run into the issues you’ve described. The partition is 4G (/var/log), however ls -lh /var/log/lastlog believes it is 465GB (four hundred and sixty-five GB). However, a df -PhT /var/log shows only 65M (sixty-five MB) being actually used. The /var/log is on an xfs local file system.