Geospatial Systems - 2D Geometry

A. Geometry primitives (2D)

* POINT (30 10)
- eg a single wifi hostspot
* LINESTRING (30 10, 10 30, 40 40)
- eg a single road a river, etc
* POLYGON
a. ((30 10, 10 20, 20 40, 40 40, 30 10)) - eg simple (ir)regular shape
b. ((35 10, 10 20, 15 40, 45 45, 35 10),(20 30, 35 35, 30 20, 20 30)) - with inner + exterior ring eg a doughnut


B. Multipart geometries (2D)
* MULTIPOINT ((10 40), (40 30), (20 20), (30 10)) or MULTIPOINT (10 40, 40 30, 20 20, 30 10)
- eg several wifi hotsposts in a given area

* MULTILINESTRING ((10 10, 20 20, 10 40),(40 40, 30 30, 40 20, 30 10))
- eg several roads and possibly crossing each other

* MULTIPOLYGON (((30 20, 10 40, 45 40, 30 20)),((15 5, 40 10, 10 20, 5 10, 15 5)))
- eg a marp showing several wards in a constituency

Linux Cron Jobs

Cron Jobs aka Scheduled Tasks

1. To see crontabs for root
#crontab -u root -l


2. To edit
#crontab -u root -e
Edit the time (min hh) to 00 10 - so that this task runs every day at 10 a.m.


a. Run at 9pm everyday
00 21 * * * wget -q "http://192.168.1.254:9090/bizypalace/push?to=0202058726&msg=NOTICE (9 PM) Server OK: $(date)"

b. At midnight 00 00 hours everyday
00 00 * * * wget -q "http://192.168.1.254:9090/bizypalace/push?to=0202058726&msg=CRON AT MIDNIGHT"

c. every 2 hours from 4am till 6pm
00 04,06,08,10,12,14,16,18 * * *

Note: in my examples am running wget but u can use any bash command

3. To check Log
tailf /var/log/cron