| Re: bidirectional pipe by Spawn on UNIX [message #16857] |
Mon, 23 August 1999 00:00 |
fireman
Messages: 49
Registered: August 1991
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Member |
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Ivo Labbe (ivo@strw.leidenuniv.nl) wrote:
: While writing to an piped shell process from IDL in an unix environment
: goes fine, I seem to be unable to read from it. Type conversion errors
: all over the place. I'm obviously doing something wrong and IDL help is
: not explicit on the subject. What is the preferred way to read the
: output from a spawned piped child process?
Variables read from a bidirectional pipe must be declared with the
correct in advance. Strings must be of the correct length. I have a
Fortran example below (well, it worked 4 years ago, anyway :)
pro demo, mult, out, colors
mult = fix(mult) ; make sure multiplier is integer
in = indgen(10) ; initialize input array
out = in ; initialize output array
colors = replicate('0123456789', 7) ; initialize string array
spawn, 'demo', unit = lun ; open bi-directional pipe
printf, lun, in, mult, out ; pass variables to pipe
readf, lun, in, mult, out, colors ; get variables from pipe
free_lun, lun ; close bi-directional pipe
return
end
C compile using "f77 -o demo demo.f"
program demo
implicit none
integer in(10), mult, out(10), i
character*10 colors(7)
C
C Read input parameters
C
read *, in, mult, out
C
C Calculate output array
C
do 10 i = 1, 10
out(i) = in(i) * mult
10 continue
C
C Define character array
C
colors(1) = 'red'
colors(2) = 'orange'
colors(3) = 'yellow'
colors(4) = 'green'
colors(5) = 'blue'
colors(6) = 'indigo'
colors(7) = 'violet'
C
C Print output parameters
C
print *, in, mult, out
do 15 i = 1, 7
print *, colors(i)
15 continue
stop
end
--
-- Gwyn F. Fireman
-- General Sciences Corporation / MODIS Characterization Support Team
-- Gwyn.Fireman@gsfc.nasa.gov 301-352-2118
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