[vox-tech] bash question - how to read specifed amnt of data from a file

dylan vox-tech@lists.lugod.org
Wed, 08 Oct 2003 22:49:11 -0800


hi-

been playing around with using a basic stamp II to collect environmental
data with very minimal setup (CdS cell and capacitor form an RC network, RC
constant is measured by BS II)
[http://surfdavis.no-ip.com/~dylan/light_level.p2.png]

the BSII sends its data to /dev/ttyS0, and it is read in with the
command'cat /dev/ttyS0 > tmp.light &' . data is parsed by a simple awk
script and then sent to ploticus for a nice plot. the plot is updated by
running a shell script that runs the awk sript and then ploticus.

this works, but there is no way to associate a time with the data values. i
was thinking that if there was some way to have a bash script read from
/dev/ttyS0 every 10 seconds or so, save the value to a text file along with
a date stamp it would be pretty neat.

the output from the BSII looks something like this:
light_level|light_level|light_level   and so on (the delimiter is a pipe)

now to the question: does anyone know how to make bash read from a file
(i.e. the serial port) from one pipe until another pipe, and then save the
value in between to a text file?

i know this is asking a lot, but any pointers would be great!

thanks a lot!

dylan