Computing, GIS and Archaeology in the UK

Never apologise for delayed posts… this is a Sunday Tip Day post, not a Thursday! Anyhow…

I just found a super little cross-platform utility that takes shapefiles and dumps them to a variety of text-based formats. Download it here, and simply unzip it to use it.

There isn’t much documentation, but basically your options are to download to gpx or spreadsheet. The following gives you a simple delimited text file with the coordinates and values from your attribute table:

./shp2text -–spreadsheet /path/to/your/shapefile.shp > /path/to/output.txt

Bob is indeed your mother’s brother.

Apologies for the delay- it’s been a roller-coaster week at Archaeogeek Towers due to family health issues. Hopefully it’s getting sorted now though.

In the process of preparing Portable GIS, I needed to change a string in multiple files of multiple formats within multiple folders. I looked at various windows- based options, most of which had a charge associated with them, but one of my colleagues suggested a linux approach.

“Sed” is the command that you need, found in most linux systems. In windows you can install it as part of the unxutils toolkit. The following command in linux works recursively through the folders in a root directory changing string1 for string2 (be careful with those single quotes if copy and pasting as wordpress likes to restyle them):

find ./ -type f -exec sed -i ’s/string1/string2/’ {} \;

With a large number of files this might take some time to work (a usb stick took an hour to work through on my ubuntu server vm but maybe that’s not a fair benchmark).

How to mount a USB stick in Ubuntu server using the command prompt only:

Do a sudo tail -f /var/log/syslog and plug the usb drive in.
Look for lines like these:
Feb 18 12:58:32 shuchi kernel: [17192272.616000] sda: assuming drive cache: write through
Feb 18 12:58:32 shuchi kernel: [17192272.616000] sda: sda1

Make a directory in /media named usbdrive.
Mount it like this: sudo mount /dev/sda1 /media/usbdrive

To unmount before ejecting:
sudo umount /media/usbdrive

If you get a message saying that the device is busy you can find out what process is using it using with the fuser command, with the -u parameter to see which user it is:

fuser -u /media/usbdrive

This will give you a number which refers to a process, and a user, then run ps -A to list all the processes and see which one it is. If you need to kill that process (USE WITH CAUTION) then run:

sudo kill -9 yourprocessnumber

You should then be able to safely unmount your USB drive

February’s quick links:

• Via my new colleague (Hi Ben), some tutorials for using QGIS and GRASS as opposed to (or in conjunction with) ArcGIS on an archaeological project
• Andlinux- a different way of accessing linux-based programmes without going through cygwin.  I’ve managed to get GRASS installed, though I haven’t tried it out in anger yet.
• A n00bs guide to installing linux programmes from source. Don’t be scared, it’s not that bad, though I’d add in how to get the command line to send it’s output to a log file for those times when it all goes wrong and you didn’t happen to catch the error as it scrolled past really fast…