Remove x lines form top and y lines form bottom using AWK? Post: 302724659

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Top Forums Shell Programming and Scripting Remove x lines form top and y lines form bottom using AWK? Post 302724659 by cfajohnson on Thursday 1st of November 2012 06:03:19 AM

11-01-2012

Registered User

Code:

## NAME: topntail
## USAGE: topntail [-b N] [-e N] [FILE ...]

b=1  ## No. of lines to remove from beginning
e=1  ## No. of lines to remove from end

## Parse command-line options
while getopts b:e: opt
do
  case $opt in
      b) b=$OPTARG ;;  ## Number of lines to remove from beginning
      e) e=$OPTARG ;;  ## Number of lines to remove from end
  esac
done
shift $(( $OPTIND - 1 ))

case $b$e in   ## check for non-numeric characters in $b and $e
    *[!0-9]*) exit 5 ;;
esac

if [ $e -eq 0 ]
then
  sed "1,${b}d" "$@"  ## just remove from the top
else
  ## The buf[] array is a rotating buffer which contains the last N lines
  ## where N is the number of lines to be removed from the bottom of the file
  ## Printing starts when the line number is equal to the sum of the number
  ## of lines to be removed from top and bottom, and continues to the end
  ## of the file; the earliest line in the buffer is printed.
  ## The last N lines will not be printed.
  awk 'NR > b + e { print buf[ NR % e ] }
                  { buf[ NR % e ] = $0 }' b=$b e=$e "$@"
fi

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LEARN ABOUT CENTOS

git-stripspace

GIT-STRIPSPACE(1)						    Git Manual							 GIT-STRIPSPACE(1)

NAME

       git-stripspace - Remove unnecessary whitespace

SYNOPSIS

       git stripspace [-s | --strip-comments] < input

DESCRIPTION

       Clean the input in the manner used by Git for text such as commit messages, notes, tags and branch descriptions.

       With no arguments, this will:

       o   remove trailing whitespace from all lines

       o   collapse multiple consecutive empty lines into one empty line

       o   remove empty lines from the beginning and end of the input

       o   add a missing 
 to the last line if necessary.

       In the case where the input consists entirely of whitespace characters, no output will be produced.

       NOTE: This is intended for cleaning metadata, prefer the --whitespace=fix mode of git-apply(1) for correcting whitespace of patches or
       files in the repository.

OPTIONS

       -s, --strip-comments
	   Skip and remove all lines starting with comment character (default #).

       -c, --comment-lines
	   Prepend comment character and blank to each line. Lines will automatically be terminated with a newline. On empty lines, only the
	   comment character will be prepended.

EXAMPLES

       Given the following noisy input with $ indicating the end of a line:

	   |A brief introduction   $
	   |   $
	   |$
	   |A new paragraph$
	   |# with a commented-out line    $
	   |explaining lots of stuff.$
	   |$
	   |# An old paragraph, also commented-out. $
	   |	  $
	   |The end.$
	   |  $

       Use git stripspace with no arguments to obtain:

	   |A brief introduction$
	   |$
	   |A new paragraph$
	   |# with a commented-out line$
	   |explaining lots of stuff.$
	   |$
	   |# An old paragraph, also commented-out.$
	   |$
	   |The end.$

       Use git stripspace --strip-comments to obtain:

	   |A brief introduction$
	   |$
	   |A new paragraph$
	   |explaining lots of stuff.$
	   |$
	   |The end.$

GIT

       Part of the git(1) suite

Git 1.8.3.1							    06/10/2014							 GIT-STRIPSPACE(1)