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Full Discussion: C Shell - Command Inside a Loop
Top Forums Shell Programming and Scripting C Shell - Command Inside a Loop Post 302326133 by ahmad.diab on Wednesday 17th of June 2009 07:12:21 AM
Old 06-17-2009
Quote:
Originally Posted by hobbers
I have a command nested in some while loops to parse some data that looks something like this.

Code:
while ($condition)
  while ($condition)
    ...
    gzcat /dir/$fileName.gz | grep $searchString > out_file
  end
end

On the first loop, the command is executed properly (and takes maybe 10 seconds to finish). But on all subsequent loops, something happens and the command is not executed properly. I know this because the data I expect does not get output to "out_file" and the process takes a split second, whereas it should take the usual 10 seconds.

To make sure the command is not getting messed up during the looping, I put an echo just before the command is executed, so it looks like this.

Code:
while ($condition)
  while($condition)
    ...
    echo "gzcat /dir/$fileName.gz | grep $searchString > out_file"
    gzcat /dir/$fileName.gz | grep $searchString > out_file
  end
end

The echo gives me what I expect.

Code:
gzcat /dir/file1.gz | grep string1 > out_file
gzcat /dir/file2.gz | grep string2 > out_file
gzcat /dir/file3.gz | grep string3 > out_file

If I run those 3 commands in a row at the prompt manually, I get the results I expect. But inside the script, only the first loop of the command gets the results. Any ideas what could be happening?

Thanks,
hobbers


Do the following and prvide me with your feedback please:-

Code:
while ($condition)
  while ($condition)
    ...
    gzcat /dir/$fileName.gz | grep $searchString >> out_file &
    wait
  end
end

 

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LEARN ABOUT REDHAT

ppmtosixel

ppmtosixel(1)						      General Commands Manual						     ppmtosixel(1)

NAME

       ppmtosixel - convert a portable pixmap into DEC sixel format

SYNOPSIS

       ppmtosixel [-raw] [-margin] [ppmfile]

DESCRIPTION

       Reads  a  portable  pixmap  as input.  Produces sixel commands (SIX) as output.	The output is formatted for color printing, e.g. for a DEC
       LJ250 color inkjet printer.

       If RGB values from the PPM file do not have maxval=100, the RGB values are rescaled.  A printer control header and a color assignment table
       begin the SIX file.  Image data is written in a compressed format by default.  A printer control footer ends the image file.

OPTIONS

       -raw   If  specified,  each  pixel  will  be explicitly described in the image file.  If -raw is not specified, output will default to com-
	      pressed format in which identical adjacent pixels are replaced by "repeat pixel" commands.  A raw file is often an order	of  magni-
	      tude larger than a compressed file and prints much slower.

       -margin
	      If  -margin  is not specified, the image will be start at the left margin (of the window, paper, or whatever).  If -margin is speci-
	      fied, a 1.5 inch left margin will offset the image.

PRINTING

       Generally, sixel files must reach the printer unfiltered.  Use the lpr -x option or cat filename > /dev/tty0?.

BUGS

       Upon rescaling, truncation of the least significant bits of RGB values may result in poor color conversion.  If the original PPM maxval was
       greater	than  100,  rescaling  also reduces the image depth.  While the actual RGB values from the ppm file are more or less retained, the
       color palette of the LJ250 may not match the colors on your screen.  This seems to be a printer limitation.

SEE ALSO

       ppm(5)

AUTHOR

       Copyright (C) 1991 by Rick Vinci.

								   26 April 1991						     ppmtosixel(1)
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