Why is lastlog so large?

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).

What does lastlog do in Linux?

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.

How can I see var log lastlog?

Re: how to see the log of /var/log/lastlog Fredeirck, You could use strings /var/log/lastlog | more you should be able to see the file now.

Can I delete var log lastlog?

Task: Clear last login information by deleting /var/log/lastlog. Press CTR+D to save the changes.

What is a sparse file in 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.

How find large files in Linux?

The procedure to find largest files including directories in Linux is as follows:

1. Open the terminal application.
2. Login as root user using the sudo -i command.
3. Type du -a /dir/ | sort -n -r | head -n 20.
4. du will estimate file space usage.
5. sort will sort out the output of du command.

What is utmp in Linux?

The utmp file allows one to discover information about who is currently using the system. There may be more users currently using the system, because not all programs use utmp logging. Warning: utmp must not be writable by the user class “other”, because many system programs (foolishly) depend on its integrity.

What is wtmp in Linux?

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.

Who logged in last Linux?

In order to find last login times for all users on your Linux machine, you can use the “lastlog” command with no options. By default, you will be presented with the list of all users with their last login attempts. Alternatively, you can use the “-u” option for “user” and specify the user you are looking for.

How do I permanently delete Linux history?

There may come a time that you want to remove some or all the commands in your history file. If you want to delete a particular command, enter history -d . To clear the entire contents of the history file, execute history -c .

Where can I find sparse files in Linux?

Finding sparse files

1. Use find command with “%S” to find each file’s sparseness.
2. Value displayed in the leftmost column is (BLOCK-SIZE*st_blocks / st_size) which is normally less than 1.0 in case of sparse file.

What is Fallocate in Linux?

DESCRIPTION top. fallocate is used to manipulate the allocated disk space for a file, either to deallocate or preallocate it. For filesystems which support the fallocate system call, preallocation is done quickly by allocating blocks and marking them as uninitialized, requiring no IO to the data blocks.

How big is the file size of lastlog?

This is, thankfully, an illusion. The lastlog file is created as a sparse file, so only the chunks of the file that are used actually take up physical storage space. So all the space really isn’t allocated. The file size just shows you how big the would would be if you tried to copy it or if you actually had 2 32 users.

How big is / var / log / lastlog on hp?

I have a question. On my HP DL585 box running RH4, I could see huge file around 273GB – /var/log/lastlog. Whats causing this to so big ?

What are the options for the lastlog command?

The options which apply to the lastlog command are: Print only lastlog records older than DAYS . Display help message and exit. Print the lastlog records more recent than DAYS . Print the lastlog record for user with specified LOGIN only. The -t flag overrides the use of -u .

How does lastlog print the last login log?

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: Print only lastlog records older than DAYS .