So your system is acting screwy and you are tying to figure out what is going wrong. Listing the processes in order to determine who the CPU or memory hogs are.
List how much CPU percent and time each process is uing
ps -e -o pcpu,cpu,nice,state,cputime,args –sort pcpu | sed ‘/^ 0.0 /d’
In order to list the process with how much memory each process is using, listed from lease to most memory hogs.
ps -e -orss=,args= | sort -b -k1,1n | pr -TW$COLUMNS
I just want to share this simple command to show you how to list out all installed packages on a system. It is often useful when you need to compare two system, or easily check to see if you installed a package already.
dpkg –get-selections
server:/var/log/openvpn# dpkg –get-selections
acpi-support-base install
acpid install
adduser install
apache2 install
apache2-mpm-prefork install
apache2-utils install
apache2.2-common install
apt install
… and losts more
This also works on Debian like operating systems like Ubuntu. Below is a example from my Debian desktop.
user@server:~$ dpkg –get-selections|grep xserver
x11-xserver-utils install
xserver-common install
xserver-xorg install
xserver-xorg-core install
xserver-xorg-input-all install
xserver-xorg-input-evdev install
xserver-xorg-input-mouse install
xserver-xorg-input-synaptics install
xserver-xorg-input-vmmouse install
xserver-xorg-input-wacom install
xserver-xorg-video-all install
xserver-xorg-video-apm install
xserver-xorg-video-ark install
xserver-xorg-video-ati install
xserver-xorg-video-chips install
xserver-xorg-video-cirrus install
xserver-xorg-video-fbdev install
xserver-xorg-video-geode install
xserver-xorg-video-i128 install
xserver-xorg-video-i740 install
xserver-xorg-video-intel install
xserver-xorg-video-mach64 install
xserver-xorg-video-mga install
xserver-xorg-video-neomagic install
xserver-xorg-video-nv install
xserver-xorg-video-openchrome install
xserver-xorg-video-r128 install
xserver-xorg-video-radeon install
xserver-xorg-video-rendition install
xserver-xorg-video-s3 install
xserver-xorg-video-s3virge install
xserver-xorg-video-savage install
xserver-xorg-video-siliconmotion install
xserver-xorg-video-sis install
xserver-xorg-video-sisusb install
xserver-xorg-video-tdfx install
xserver-xorg-video-trident install
xserver-xorg-video-tseng install
xserver-xorg-video-v4l install
xserver-xorg-video-vesa install
xserver-xorg-video-vmware install
xserver-xorg-video-voodoo install
There are times when you need need to send E-Mail from your Linux server. The reason that I had to set up E-Mail was because I had a php script that E-Mailed me once some one filled out their information on the website. The easiest way to get your server sending mail is using GMail to send the mail. This tutorial will describe how to set it up on Ubuntu / Debian.
sudo aptitude install postfix libsasl2 ca-certificate libsasl2-modules
You want to add the fowling lines to your /etc/postfix/main.cf
relayhost = [smtp.gmail.com]:587gmail_passwd
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/
smtp_sasl_security_options = noanonymous
smtp_tls_CAfile = /etc/postfix/cacert.pem
smtp_use_tls = yes
You need to edit /etc/postfix/gmail_passwd and add the fowling information below, edit it to fit your needs.
[smtp.gmail.com]:587 UserMame@gmail.com:PassWord
Next you need to turn the gmai_passwd file into something that postfix can understand, you can use the command below to accomplish that.
sudo chmod 400 /etc/postfix/sasl_passwd
sudo postmap /etc/postfix/sasl_passwd
Now you can restart postfix but it will complain about not being able to authenticate the certificate. In order to fix the problem we will use the ca-certificate package we installed earlier to tell it where it can validate the certificate.
cat /etc/ssl/certs/Thawte_Premium_Server_CA.pem | sudo tee -a /etc/postfix/cacert.pem
Now restart postfix for the final time.
/etc/init.d/postfix