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Linux: View what users are / were logged on a system

christian — Fri, 16 Jul 2010 06:56:08 +0000

There are several simple commands to show what users are logged a Linux systems.

The following commands are standard in all distributions (as of date)

who

who –a

who and users show who are currently logged on. You can also use last:

last

Another possibility is to get the users-information from the systems logs:

grep sshd /var/log/messages

grep-out Failed login attempts

grep sshd /var/log/messages | grep -i "Failed" | awk ‘{print $NF}’ | sort|uniq -c|sort -n

see access thru httpd

cat /var/log/httpd/access_log

Linux: Find large files using find command

christian — Tue, 04 Aug 2009 10:57:37 +0000

To searach for files larger than 100mb (approx.):

find / -type f -size +100000k

Change Date or Time on Linux

christian — Tue, 04 Aug 2009 09:24:16 +0000

Under most configurations, you must be logged on as “root” to make this change. You can log on locally (physically at the Linux box) as root. However, if you must perform this remotely (over a network or the Internet), you need to first log on to the machine under a user that will allow you to log on remotely. Then “switch user” to “root” by typing “su” at the prompt and pressing enter. When prompted, type root’s password and press enter.

To change the time from the bash prompt, as root, use the “date” command. Typing “date” by itself will return the date, time, and year. Typing “date MMDDhhmmCCYY” will allow you to set any part of the date or time.
Linux Examples:

[me@mybox me]$ su password:

Check the current date and time of the Linux box by entering:

[root@mybox me]# date [root@mybox me]# Tue Aug 4 12:03:45 CEST 2009

Change the current time and date of the Linux box by entering:

Format is:

2-digits month => 08
2-digits day => 04
2-digits hour => 12
2-digits minutes =>03
4-digits year =>2009

[root@mybox me]# date 080412032009 [root@mybox me]$ Tue Aug 4 12:03:00 CEST 2009