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Full Discussion: Combine awk commands into one
Top Forums Shell Programming and Scripting Combine awk commands into one Post 302979708 by bakunin on Thursday 18th of August 2016 05:56:08 AM
Old 08-18-2016
As a general remark about one-liners: one-liners reduce readability and understandability. Their advantage is that they can be fastly written.

Given that you are unable to modify your already existing one-liners (which i take as a hint that you are not completely understanding them already) i suggest that it is a bad idea to combine these to an even more complex construct which you are bound to understand even less.

It is of course always possible to rely on us (or other people like us) to provide modifications as the code will need to be modified but, honestly: do you really want to preside over an environment where you do not understand what is going on? It might be me but i for my part would have a very bad feeling being in such a position.

It is in your own best interest if you rely on us only if you need an explanation to further your understanding but not to write or modify your productive code. Whatever you use finally you should be able to produce on your own and you should write it in a way that you are able to understand its inner workings.

Btw., over time i found that restricting my written code to 80 characters per line with only select few exceptions (for instance definitions of string constants) makes my code more readable and better overall. The reason is that a line containing more than 80 characters is most likely badly formed and should be rewritten in a more conclusive manner anyways. This in most cases means i reformat one-liners to their long form.

Here is an example where i filter out comments and whitespace from an input file before processing:

Code:
sed 's/#.*//;s/^[ 	]*//;s/[ 	]*$//;/^$/d' "$fCmd" | while read chCmd ; do
     .....
done

Going over that code i modified it to:

Code:
sed 's/#.*//
     s/^[ 	]*//
     s/[ 	]*$//
     /^$/d' "$fCmd" |\
while read chCmd ; do
     .....
done

I'd say the second variant gives you a much cleaner and easier to grasp impression of what is going on than the first.

I hope this helps.

bakunin
This User Gave Thanks to bakunin For This Post:
RudiC
 

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LEARN ABOUT OPENSOLARIS

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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