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Full Discussion: Help understand awk command
Top Forums UNIX for Beginners Questions & Answers Help understand awk command Post 303040548 by RudiC on Thursday 31st of October 2019 10:15:12 AM
Old 10-31-2019
Quote:
Originally Posted by mohan44
...
This command converts the column values to rows.
...
I'm afraid it doesn't as it has a syntax error. Did you run it as given?
Upfront variable definition needs the -v option.
Quote:
is converted to:
1, 2, 3
Not quite - there are spaces before the commas.





Once you corrected that, it uses a "conditional assignment" to check the S variable and, if non-null, adds the actual input line ($0) enclosed in spaces to it, else assigns it just the latter.


This does similar thigs making use of awk's default bebaviour:
Code:
awk '$1=$1' RS= OFS=, file
1,2,3

 

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LEARN ABOUT REDHAT

ppmtopgm

ppmtopgm(1)						      General Commands Manual						       ppmtopgm(1)

NAME

       ppmtopgm - convert a portable pixmap into a portable graymap

SYNOPSIS

       ppmtopgm [ppmfile]

DESCRIPTION

       Reads  a  portable  pixmap  as  input.  Produces a portable graymap as output.  The output is a "black and white" rendering of the original
       image, as in a black and white photograph.  The quantization formula used is .299 r + .587 g + .114 b.

       Note that although there is a pgmtoppm program, it is not necessary for simple conversions from pgm to ppm , because any  ppm  program  can
       read  pgm  (and	pbm  ) files automatically.  pgmtoppm is for colorizing a pgm file.  Also, see ppmtorgb3 for a different way of converting
       color to gray.  And ppmdist generates a grayscale image from a color image, but in a way that makes it easy to differentiate  the  original
       colors, not necessarily a way that looks like a black and white photograph.

QUOTE

       Cold-hearted orb that rules the night
       Removes the colors from our sight
       Red is gray, and yellow white
       But we decide which is right
       And which is a quantization error.

SEE ALSO

       pgmtoppm(1),ppmtorgb3(1),rgb3toppm(1),ppmdist(1),ppm(5),pgm(5)

AUTHOR

       Copyright (C) 1989 by Jef Poskanzer.

								   10 April 2000						       ppmtopgm(1)
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