Himeji IT Study Vol.11 L-1 GP 3.tail

tail.sh

#!/bin/bash

parse_options(){
  N=5 # default line number
  while getopts "n:" OPT; do
    case ${OPT} in
      n) N="$OPTARG" ;;
    esac
  done
  shift $(($OPTIND-1))
  FILENAME=$@
}

# sed version
sed_version(){
  if [ "${START_LINE}" -gt "0" ]; then 
    sed "1,${START_LINE} d" ${FILENAME}
  else
    cat ${FILENAME}
  fi
}

# while version
while_version(){
  IFS=$'\n'
  i=1
  while read LINE;do
    [ ${i} -gt ${START_LINE} ] && echo "${LINE}"
    let ++i
  done < ${FILENAME}
}

parse_options "$@"
END_LINE=$(wc -l ${FILENAME}|cut -f1 -d" ")
START_LINE=$((${END_LINE} - ${N}))

#sed_version
while_version