When checking a server access logs, you may wnat to see how many time an IP is requesting pages. Here is the command:

grep 123.123.123.123 /usr/local/apache/logs/error_log | wc -l
1018

First, you need to download the file using Wget and then install it using RPM on your system to enable the EPEL repository.

RHEL/CentOS 7 64 Bit

# wget http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
# rpm -ivh epel-release-latest-7.noarch.rpm

## RHEL/CentOS 6 64-Bit ##

# wget http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
# rpm -ivh epel-release-6-8.noarch.rpm

Check the installation

# yum repolist
*epel/x86_64 Extra Packages for Enterprise Linux 7 - x86_64

Now, install stress

# yum install stress

To test, first run the uptime command and note down the load average. Next, run the stress command to spawn 8 workers spinning on sqrt() with a timeout of 20 seconds. After running stress, again run the uptime command and compare the load average.

# uptime
16:39:03 up 1 day, 18:32,  1 user,  load average: 0.15, 0.24, 0.14

sudo stress --cpu  8 --timeout 20
stress: info: [65429] dispatching hogs: 8 cpu, 0 io, 0 vm, 0 hdd
stress: info: [65429] successful run completed in 20s

Now uptime again

# uptime
 16:40:18 up 1 day, 18:34,  1 user,  load average: 1.35, 0.59, 0.27

Spawn 8 workers spinning on sqrt() with a timeout of 30 seconds

]# uptime
16:41:52 up 1 day, 18:35, 1 user, load average: 0.28, 0.43, 0.24
[root@server rogerp]# sudo stress –cpu 8 -v –timeout 30s
stress: info: [65654] dispatching hogs: 8 cpu, 0 io, 0 vm, 0 hdd
stress: dbug: [65654] using backoff sleep of 24000us
stress: dbug: [65654] setting timeout to 30s
stress: dbug: [65654] –> hogcpu worker 8 [65655] forked
stress: dbug: [65654] using backoff sleep of 21000us
stress: dbug: [65654] setting timeout to 30s
stress: dbug: [65654] –> hogcpu worker 7 [65656] forked
stress: dbug: [65654] using backoff sleep of 18000us
stress: dbug: [65654] setting timeout to 30s
stress: dbug: [65654] –> hogcpu worker 6 [65657] forked
stress: dbug: [65654] using backoff sleep of 15000us
stress: dbug: [65654] setting timeout to 30s
stress: dbug: [65654] –> hogcpu worker 5 [65658] forked
stress: dbug: [65654] using backoff sleep of 12000us
stress: dbug: [65654] setting timeout to 30s
stress: dbug: [65654] –> hogcpu worker 4 [65659] forked
stress: dbug: [65654] using backoff sleep of 9000us
stress: dbug: [65654] setting timeout to 30s
stress: dbug: [65654] –> hogcpu worker 3 [65660] forked
stress: dbug: [65654] using backoff sleep of 6000us
stress: dbug: [65654] setting timeout to 30s
stress: dbug: [65654] –> hogcpu worker 2 [65661] forked
stress: dbug: [65654] using backoff sleep of 3000us
stress: dbug: [65654] setting timeout to 30s
stress: dbug: [65654] –> hogcpu worker 1 [65662] forked
stress: dbug: [65654] <-- worker 65659 signalled normally stress: dbug: [65654] <-- worker 65658 signalled normally stress: dbug: [65654] <-- worker 65660 signalled normally stress: dbug: [65654] <-- worker 65656 signalled normally stress: dbug: [65654] <-- worker 65655 signalled normally stress: dbug: [65654] <-- worker 65657 signalled normally stress: dbug: [65654] <-- worker 65662 signalled normally stress: dbug: [65654] <-- worker 65661 signalled normally stress: info: [65654] successful run completed in 30s [root@server rogerp]# uptime 16:43:10 up 1 day, 18:37, 1 user, load average: 1.87, 1.06, 0.49 [/bash]

One of the most common requests and inquirys is “Do I have the …xyz package or program installed?” Here is how to check.

Ubuntu/Debian

List all packages

# dpkg -l | less

# dpkg -s apache-perl

To check whether a package is installed or not:

dpkg -l | grep vlc

Use file /var/lib/dpkg/available to find out all package names available to you. Or use following command (list all packages in /var/lib/dpkg/status):

# dpkg-query -l

You can also try to match package name using wild cards:

# dpkg-query -l 'libc6*'

Use the following command to get exact status (whether it is installed or not):

# dpkg-query -W -f='${Status} ${Version}\n' apache-perl

CentOS and RPM based Distros

Under Red Hat/Fedora/CentOS/Suse Linux use the rpm command:

# rpm -qa | grep {package-name}

For example find out package mutt installed or not:

# rpm -qa | grep mutt

On a CentOS/RHEL use the following yum command to tell whether a package named htop is installed:

# yum list installed {PACKAGE_NAME_HERE}

[/bash]

# yum list installed htop

Here is a way to see what IP’s are accessing the website domain.com. Find the location of the access logs.

In a cpanel account:

# cd /home/domain.com/access-logs

Now run the following on the access logs…

# cat domain.com | awk '{print $1}' | sort | uniq -c | sort -rn | head

Here is the readout:

 24 72.178.xxx.xx
 18 216.xx.xxx.161
 1 216.55.xxx.xx

If you do see excessive bots, try adding in a crawl rate/delay for the site with Bing Webmaster tools, Google Webmaster tools as well as setting that up in robots.txt ). Webcrawlers can carelessly crawl the site and hit it hard, just to index pages.