How to swap a column in Calc:

Select column B

Click anywhere in the highlighted area and drag the column. The mouse pointer should change to show the drag operation.

Before you release the mouse button, also press the Alt key. When the mouse pointer is at the left side of column A, release the mouse button.

Column B should be moved to the left of column A so that A and B are switched.

vi /path/to/message.sh

#!/bin/bash
PID=$(pgrep gnome-session)
dbus=$(grep -z DBUS_SESSION_BUS_ADDRESS /proc/$PID/environ|cut -d= -f2-)
export DBUS_SESSION_BUS_ADDRESS=$dbus
notify-send -u critical "$1"

crontab:

0 * * * * /path/to/message.sh "my message"

vi /etc/systemd/system/mongodb.service

[Unit]
Description=High-performance, schema-free document-oriented database
After=network.target

[Service]
User=mongodb
ExecStart=/usr/bin/mongod --quiet --config /etc/mongod.conf

[Install]
WantedBy=multi-user.target

systemctl start mongodb systemctl enable mongodb

vi /etc/systemd/system/elastic.service

[Unit]
Description=Port forwarding for 9200
After=network.target

[Service]
User=javelin
ExecStart=/usr/bin/ssh -NTC -o ServerAliveInterval=60 -o ExitOnForwardFailure=yes -o StrictHostKeyChecking=no -R 9201:15.0.33.22:9200 user@host.com
RestartSec=3
Restart=always

[Install]
WantedBy=multi-user.target

systemctl start elastic

systemctl enable elastic

https://blog.kylemanna.com/linux/ssh-reverse-tunnel-on-linux-with-systemd/

    screen -ls
    screen -dmS mytabname php artisan dosomething
    screen -r mytabname

    detach:
    ctrl+a , d

    ls -laR /var/run/screen/

1. Install drivers (http://support.displaylink.com/knowledgebase/articles/684649-how-to-install-displaylink-software-on-ubuntu)

2. Disable secure boot

3. Create file:

   $ vi /usr/share/X11/xorg.conf.d/10-intel.conf

Paste This:

    Section "Device"
        Identifier  "Intel"
        Driver      "intel"
        Option      "VSync" "false"
    EndSection

Best Solution:

$ cat /etc/X11/xorg.conf.d/20-intel.conf
Section "Device"
    Identifier "Intel Graphics"
    Driver "Intel"
    Option "AccelMethod" "sna"
    Option "TearFree" "true"
    Option "TripleBuffer" "true"
    Option "MigrationHeuristic" "greedy"
    Option "Tiling" "true"
    Option "Pageflip" "true"
    Option "ExaNoComposite" "false"
    Option "Tiling" "true"
    Option "Pageflip" "true"
    Option "VSync" "false"
EndSection

1. Reboot

2. CPU decreasing compiz https://askubuntu.com/questions/689602/disable-all-visual-effects-in-ubuntu-15-10

Before installation

mysite.com MX record points to mysite.com

Step 1

Need to do https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-postfix-on-ubuntu-16-04

Step 2

Setup all, except ClamAV (if RAM is enough, ClamAV can be installed) https://help.ubuntu.com/community/PostfixAmavisNew How to siable ClamAV:

# @\bypass_virus_checks_maps = (
#    \%bypass_virus_checks, \@\bypass_virus_checks_acl, \$bypass_virus_checks_re);

Step 3

Instead Dovecot i prefer this https://help.ubuntu.com/community/PostfixBasicSetupHowto

Installing courier IMAP and POP3

apt install courier-pop
apt install courier-imap

Then

service courier-authdaemon start

systemctl enable courier-authdaemon

/etc/init.d/postfix restart

Step 4

Setup SPF

https://www.digitalocean.com/community/tutorials/how-to-create-a-spf-record-for-your-domain-with-google-apps

Step 5

Setup DKIM

https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-dkim-with-postfix-on-debian-wheezy

Step 6

Setup DMARK

https://habrahabr.ru/company/mailru/blog/170957/

tail /var/log/auth.log
find . -type f -newermt 2017-01-01 ! -newermt 2017-01-31

grep -lr --include=*.php "base64_decode"
grep -lr --include=*.php "@require"