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

3 Dec 2011


      On Tuesday 29 November 2011 21:57:42 David C. Rankin wrote:
...
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"
  }
}
If you're still inclined to go the bash way, perhaps something like this would 
work (parameter validation and other sanity checks omitted):

function ellipse() {
  str="${1}"
  lim="${2}"
  rem=${3:-3}
  char=${4:-.}
 
  [[ ${#str} -gt ${lim} ]] && 
  { 
    begin=${str:0:$((lim-rem))}; 
    end=${str:$((lim-rem)):${rem}}; 
    echo ${begin}${end//?/${char}}; 
  } || echo "${str}" 
}


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

Martti Laaksonen