Combine awk commands into one Post: 302979708

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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

08-18-2016

Registered User

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

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LEARN ABOUT DEBIAN

deweb

deweb(1)						      General Commands Manual							  deweb(1)

NAME

       deweb - strips away C & CWEB commands from CWEB sources

SYNOPSIS

       deweb [ file1 file2 ...	]

DESCRIPTION

       deweb filters away all C & CWEB commands from a CWEB source code. This leaves only the LaTeX code. This stripped code, in turn, may then be
       passed to a suitable syntax checker for LaTeX, like ChkTeX and lacheck, or spell-checkers like ispell.

       The chkweb tool, included in the ChkTeX distribution will do just this; writing similar scripts should be trivial.

       When deweb strips away the C code from your CWEB source, it tries to preserve line breaks.  This means that the error reports   from  <your
       favorite  tool> will be correct regarding to line numbers. In most cases, the column position will also be correct. This significantly sim-
       plifies finding the errors in the LaTeX source (in contrast to the output from cweave, which output is truly difficult to  figure  anything
       out from).

       deweb  accepts  a list of filenames on the argument line, and will send its output to stdout.  If no filenames are given, it will read from
       stdin, acting as a filter. No options are currently accepted.

       Macho users may try to pipe the output from deweb directly into LaTeX, theoretically, this should work. This would ease	the  debugging	of
       the LaTeX code significantly, as when LaTeX complains about wrong syntax, you'll be able to find the erroneous line much more easily. Don't
       expect that the output looks very much like the final one, though.

       deweb should now understand all correct CWEB opcodes. If it complains about not understanding a correct opcode, please inform the author.

DISTRIBUTION

       Copyright (C) 1996 Jens T. Berger Thielemann

       This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as  published	by
       the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

       This  program  is  distributed  in  the	hope  that  it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MER-
       CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

       You should have received a copy of the GNU General Public License along with this program; if not, write to the Free  Software  Foundation,
       Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

ENVIRONMENT

       No environment variables are used.

FILES

       None.

AUTHOR

       Jens T. Berger Thielemann, <jensthi@ifi.uio.no>

SEE ALSO

       cweave(1), perl(1), chktex, lacheck(1), ispell(1)

BUGS

       Doesn't	even  compile  under  Perl versions before perl v5. Unfortunately, this means that we can't even tell the user why we failed; Perl
       will just complain about not being able to compile the regexps.

       The program will try to swallow the whole input file at once, instead of processing it on a line-by-line basis.

7th Edition							   June 8, 1996 							  deweb(1)

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