#!/bin/sh
################################
## Get rid of a number of beginning and/or ending characters on each line
## Usage: suck [NUMBER] [-a NUMBER] [-b NUMBER] [-h]
##   -a  Suck away the last NUMBER of characters on each line
##   -b  Suck away the first NUMBER of characters on each line (default)
##   -h  Show help screen
## Example: ls -l |suck 16   # suck out the permsissions and number of links.
## suck 1.0, Copyright (c) 2003 by Adam Katz <scripts@khopis.com>, GPL
################################

# no args -> help
[ "y$1" = "y" ] && set -- "-help"

# parse arguments
while [ "y$1" != "y" ]; do
  # --help -h* --h* h
  if echo $1|grep -qE "^--*h"; then
    # cygwin can't deal with `which $0` if $0 is a full path
    me=`which $0 2>/dev/null`; [ "x$me" = "x" ] && me="$0"
    grep "^\#\# " $me|sed -e 's/^...//'
    exit 0

  # number
  elif echo $1|grep -q "^[0-9]*$"; then
    before="s/^.\{$1\}//"

  # -b* --b* -B* --B* with a space before number
  elif echo $1|grep -qEi "^--*b[^0-9]*$"; then
    if echo $2|grep -q "^[0-9]*$"
      then before="s/^.\{$2\}//"
      else echo "$0: -b value \`$2\' not a number"|sed 's:.*/::g' 1>&2
    fi
    shift
  # -b* --b* -B* --B* ending in number
  elif echo $1|grep -qEi "^--*b.*[0-9]$"; then
    before="s/^.\{`echo $1|sed -r -e "s/^--*b[^0-9]*//i"`\}//"
  
  # -a* --a* -A* --A* with a space before a number
  elif echo $1|grep -qEi "^--*a[^0-9]*$"; then
    if echo $2|grep -q "^[0-9]*$"
      then after="s/.\{$2\}$//"
      else echo "$0: -a value \`$2\' not a number"|sed 's:.*/::g' 1>&2
    fi
    shift
  # -a* --a* -A* --A* ending in number
  elif echo $1|grep -qEi "^--*a[0-9]"; then
    after="s/.\{`echo $1|sed -r -e "s/^--*a//i"`\}$//"

  # file or sed arg (sed conveniently does not have -a, -b, -A, or -B)
  else break
fi
shift
done

# bash magically hands the instream to sed

if [ "a$before" = "a" ]; then
  sed -e "$after" $@
elif [ "a$after" = "a" ]; then
  sed -e "$before" $@
else 
  sed -e "$before" -e "$after" $@
fi