Re: 'Cat' feature request

[Kaz Kylheku]

On 2023-12-25 19:53, Kaz Kylheku wrote:
> There are ways to speed it up by taking advantage of the contents of
> the * expansions being sorted. We change the requirements to this:
> we look for situations when the command line contains, as a contiguous
> subsequence, the sequence produced by *.

Like this, which is much faster; it takes about 0.14s in a directory of 2834 
files,
where the previous one would take numerous seconds.

cat()
{
  local -a orig_args=("$@")
  local -a star_files=(*)
  local star_seq_present=
  local found=
  local i
  local j

  # Crudely skip arguments that look like options
  while true; do
    case "$1" in
      -* | --* ) shift ;;
      * ) break ;;
    esac
  done

  # get remaining args into args array
  local -a args=("$@")

  # determine whether star_files is a substring of orig_args
  if [ ${#args[@]} -ge ${#star_files[@]} ] ; then
    for (( i = 0; i <= ${#args[@]} - ${#star_files[@]}; i++ )); do
      found=y
      for (( j = 0; j < ${#star_files[@]}; j++ )); do
        if [ "${args[$((i + j))]}" != "${star_files[$j]}" ] ; then
          found=
          break
        fi
      done
      if [ $found ] ; then
        star_seq_present=y
        break
      fi
    done
  fi

  if [ $star_seq_present ] ; then
    echo "cat: match for * present in command line!" 1>&2
    return 1
  fi

  command cat "${orig_args[@]}"
}

Here is what a couple of tests look like:

$ cat *
cat: match for * present in command line!
!1!
$ cat * *
cat: match for * present in command line!
!1!
$ cat abc * def
cat: match for * present in command line!
!1!
$ cat cat.sh | head -4
cat()
{
  local -a orig_args=("$@")
  local -a star_files=(*)

The !1! is a thing in my personal environment: when a command indicates
a failed or abnormal termination, the status is printed between ! symbols.