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Full Discussion: sed or awk editing help
Top Forums Shell Programming and Scripting sed or awk editing help Post 302468406 by DGPickett on Tuesday 2nd of November 2010 04:08:34 PM
Old 11-02-2010
Like many features, pretty but not fast, so you avoid them for heavy lifting if possible, but sometimes you need them even when they are slower.

Of course, if the user wanted to trim leading and trailing, these 4 would run fast, but the ones searching for space first should go last, s sed works his reges left to right, so it is best to have a selective string on the left end (I guess an Arabic/Hebrew language sed would work right to left?):
Code:
sed '
  s/^  *//
  s/,  */,/
  s/  *,/,/
  s/  *$//
 '

---------- Post updated at 04:08 PM ---------- Previous update was at 04:00 PM ----------

Quote:
Originally Posted by ctsgnb
Maybe the parsing Step, indeed, when ambiguous grouping is specified, it goes through a kind of "auto completion" step.
Also maybe using a memory copy instead of a memory mapping?.
Early sed had a limited line size, and was faster with less indirection, but gnu sed and later sed's seem to have very big or realloc()'d buffers. I don't think many programmers use a mmap()'d tmp file for the buffer. Sed is a pipe-oriented stream editor, so it would not be able to map the input file all the time, and even so, it could not write there, and of course it needs to scan intermediate product on multi-command scripts. So, I am not thinking memory map and sed at the same time. I suspect as it rewrites a line, it has an input pointer and an output pointer, and if the line is expanding, then when the pointers collide, there must be either mid-substitute moves in one buffer or copying between two buffers. I am not going to read the code, though! Smilie
 

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IGAWK(1)							 Utility Commands							  IGAWK(1)

NAME
igawk - gawk with include files SYNOPSIS
igawk [ all gawk options ] -f program-file [ -- ] file ... igawk [ all gawk options ] [ -- ] program-text file ... DESCRIPTION
Igawk is a simple shell script that adds the ability to have ``include files'' to gawk(1). AWK programs for igawk are the same as for gawk, except that, in addition, you may have lines like @include getopt.awk in your program to include the file getopt.awk from either the current directory or one of the other directories in the search path. OPTIONS
See gawk(1) for a full description of the AWK language and the options that gawk supports. EXAMPLES
cat << EOF > test.awk @include getopt.awk BEGIN { while (getopt(ARGC, ARGV, "am:q") != -1) ... } EOF igawk -f test.awk SEE ALSO
gawk(1) Effective AWK Programming, Edition 1.0, published by the Free Software Foundation, 1995. AUTHOR
Arnold Robbins (arnold@skeeve.com). Free Software Foundation Nov 3 1999 IGAWK(1)
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