Question

I am new to shell scripting and i found this function in a given script file.

##############################
# rotate_daily(filename)
rotate_daily() {
  _code=0
  _file_src=$1

  _today=`date '+%Y-%m-%d'`
  _file_dest=${_file_src}.${_today}
  if [ -f ${_file_dest} ]; then
    printk "rotate_daily(): ${_file_dest} already exist"
    _code=1
  else
    if [ -f ${_file_src} ]; then
      printk "rotate_daily(): ${_file_src} => ${_file_dest}"
      cp -p ${_file_src} ${_file_dest}
      _code=$?
      >${_file_src}
    fi
  fi
}

I understand this is kind of coping file from one location to another location. But, it is not rotating right?. could somebody explain me what it is really does.

thanks in advance for any help

Answer 1

It copies _file_src to the location file_dest unless _file_dest already exists. An informative message will be printed that tells you if the file already exists or file_src_ will be copied, It also moves _file_src only if it is a file.

EDIT: forgot to mention what the command >{_file_src} does – it simply wipes out the contents of the source file. So you will have the contents of _file_src moved to file_dest in the end and _file_src will be empty. I can’t figure why not simply do a move(with mv) and then create an empty file, but that’s your question.