lowercase + capitalize + concatenate words of a string in shell (e.g. bash)

Question

How to capitalize+concatenate words of a string?
(first letter uppercase and all other other letters lowercase)

example:
input = "jAMeS bOnD"
output = "JamesBond"

Answer 1

String manipulation available in bash version 4:

• ${variable,,} to lowercase all letters
• ${variable^} to uppercase first letter of each word
• use ${words[*]^} instead of ${words[@]^} to save some script lines

And other improvements from mklement0 (see his comments):

• Variable names in lower-case because upper-case ones may conflict with environment variables
• Give meaningful names to variables (e.g. ARRAY -> words)
• Use local to avoid impacting IFS outside the function (once is enougth)
• Use local for all other local variables ( variable can be first declared, and later assigned)
• ARRAY=( $LOWERCASE ) may expands globs (filename wildcards)
  • temporarily disable Pathname Expansion using set -f or shopt -so noglob
  • or use read -ra words <<< "$input" instead of words=( $input )

Ultimate function:

capitalize_remove_spaces()
{
  local words IFS
  read -ra words <<< "${@,,}"
  IFS=''
  echo "${words[*]^}"
}

If you want to keep alphanumeric characters only, extends the IFS built-in variable just before the read -ra words operation:

capitalize_remove_punctuation()
{
  local words IFS=$' \t\n-\'.,;!:*?' #Handle hyphenated names and punctuation
  read -ra words <<< "${@,,}"
  IFS=''
  echo "${words[*]^}"
}

Examples:

> capitalize_remove_spaces 'jAMeS bOnD'
JamesBond

> capitalize_remove_spaces 'jAMeS bOnD *'
JamesBond*

> capitalize_remove_spaces 'Jean-luc GRAND-PIERRE'
Jean-lucGrand-pierre

> capitalize_remove_punctuation 'Jean-luc GRAND-PIERRE'
JeanLucGrandPierre

> capitalize_remove_punctuation 'Jean-luc GRAND-PIERRE *'
JeanLucGrandPierre