Shell Programming and Scripting

if [ $ins = insert ].......
if [ $ins = Insert ].......
if [ $ins = insErt ].......
if [ $ins = INSERT ].......
if [ $ins = iNseRt ].......

newins=$(echo $ins |tr [:upper:] [:lower:])

${parameter^pattern}
${parameter^^pattern}
${parameter,pattern}
${parameter,,pattern}
   Case  modification.   This  expansion modifies the case of alphabetic characters in parameter.  The pattern is expanded to produce a pattern just as in pathname expansion.
   The ^ operator converts lowercase letters matching pattern to uppercase;
   The  , operator converts matching uppercase letters to lowercase.  The ^^ and ,, expansions convert each matched character in the expanded value; 
the ^ and , expansions match and convert only the first character in the expanded value..  If  pattern  is  omitted,  it  is treated like a ?, which matches every character.  
If parameter is @ or *, the case modification operation is applied to each positional parameter in turn, and the expansion is the resultant list.  
If  parameter  is  an array  variable  subscripted  with @ or *, the case modification operation is applied to each member of the array in turn, and the expansion is the resultant list.

if [ ${ins^^} = INSERT ].......

case "$ins" in
     [Ii][Nn][Ss][Ee][Rr][Tt]) echo true ;;
     *) echo false ;;
esac

#!/bin/bash
a=insert
b=Insert
c=insErt
d=INSERT
e=iNseRt
 
for i in $a $b $c $d $e
   do
     if  ( echo $i | grep -i INSERT >/dev/null  ) ; then
       echo Ok
     fi
done