UNIX for Beginners Questions & Answers

#! /usr/bin/ksh

function pReplaceCaseInsensitive
{
typeset     chInRegex="$1"
typeset     chReplacement="$2"
typeset     fIn="$3"
typeset     chOutRegex=""
typeset     chBuf=""
typeset -u chUpChar=""
typeset -l chLowChar=""
typeset    chInline=""

while [ -n "${chInRegex}" ] ; do
     chBuf="${chInRegex##?}"                  # chop off first character
     chLowChar="${chInRegex??${chBuf}}"       # get first char, invert to lower
     if print - "$chLowChar" | grep -q '[abcdefghijklmnopqrstuvwxyz]' ; then
          chUpChar="$chLowChar"
          chOutRegex="${chOutRegex}[${chLowChar}${chUpChar}]"
     else
          chOutRegex="${chOutRegex}${chInRegex%%${chBuf}}"
     fi
     chInRegex="$chBuf"
done

if [ -n "$fIn" ] ; then                       # deal with input from a file if specified
     if [ -r "$fIn" ] ; then
          sed 's/'"$chOutRegex"'/'"$chReplacement"'/g' "$fIn"
     else
          print -u2 "file $fIn is not readable or does not exist."
          return 1
     fi
else                                        # deal with input from stdin otherwise
     while read chInLine ; do
          print - "$chInLine" | sed 's/'"$chOutRegex"'/'"$chReplacement"'/g'
     done
fi

return 0
}

# main()

# first variant: use in a pipeline:
print - "Willy willy WIlLy test" | pReplaceCaseInsensitive 'willy' "Text"
# produces: "Text Text Text test"
print - "Willy willy WIlLy test" | pReplaceCaseInsensitive 'willy *' "Text"
# produces: "TextTextTexttest" (space gets eaten by the regexp " *")

# second variant: use with a file
pReplaceCaseInsensitive 'willy' "TEST" myfile

exit 0

# cat myfile
Willy
willY
WiLlY
bla

TEST
TEST
TEST
bla

nas1:/var/core/test        /test
nas1:/var/core/test/test2  /test1

sed 's#nas1:/var/core/test #\U&#' file
NAS1:/VAR/CORE/TEST        /test
nas1:/var/core/test/test2  /test1