[opensuse] BASH - rankinism - best way to trim string and add ellipses (or other char)?

29 Nov 2011

      DH, All,

  I want a function 'ellipse' that will take a string 'str' and trim it to
length 'len' and set the 'end' number (default = 3) of characters to 'chr'
(default='.'). So if I call it like this:

myvar=0123456789

echo "mydefvar: $(ellipse $myvar 7)"
echo "mynewvar: $(ellipse $myvar 7 3 '*')"

  I get:

mydefvar: 0123...
mynewvar: 0123***

  What I have come up with is the following, but I would like comment on how to
make it better, etc.. Is there a way to eliminate the for loop and just use
string substitution to overwrite the last 'end' number of characters with 'chr'
that would be more efficient? What says the brain trust.

ellipse() {

  # validate sufficient parameters passed
  [[ -z $1 ]] || [[ -z $2 ]] && { echo "ERROR: Insufficient input in fxn
ellipse"; return 1; }

  str="$1"
  lim="$2"
  end=${3:-3}
  chr=${4:-.}

  # validate integers
  [ $lim -eq $lim ] 2>/dev/null || return 1
  [ $end -eq $end ] 2>/dev/null || return 1

  [[ ${#str} -gt $lim ]] && newstr=${str:0:$((lim-end))}
  {
    for((i=$((lim-end));i<$lim;i++)); do
      newstr=${newstr}${chr}
    done

    echo "$newstr"
  } || {
    echo "$str"
  }
}

-- 
David C. Rankin, J.D.,P.E.
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