tee命令的shell script实现

#!/bin/sh

# Almost same function as tee command
#
# Author
#   Hansel <hansel@163.com>
# Date 2011-10-11

APPEND=0
IGNORE_INT=0

#--------------------------------------------------------------
usage() {
  cat << END
Usage: $PROG_NAME [options] <FILE>
    Copy standard input to FILE, and also to standard output.
options:
    -a          append to the given FILE, do not overwrite
    -i          ignore interrupt signals 
    -h          show this help
END
}

#-------------------- main -------------------------------------
PROG_NAME=`basename $0`

# get command line arguments
while getopts "aih" options; do
  case "$options" in
    a) APPEND=1 ;;
    i) IGNORE_INT=1 ;;
    h) usage; exit 0;;
    \?)     usage; exit -1;;
  esac
done
shift $((OPTIND - 1))

if [ $# -le 0 ];then
  echo "please give a file name for output."
  usage
  exit -1;
fi

FILE=$1

if [ $IGNORE_INT -eq 1 ]; then
  trap "" SIGINT
fi

#clear content if FILE is exited and not append mode
if [ $APPEND -eq 0 ]; then
  echo -n > $FILE;
fi

while read line; do
  echo $line;
  echo $line >> $FILE;
done;