Korn shell script function to convert and translate regular expressions into Korn shell patterns.

#!/usr/bin/ksh93
################################################################
function usagemsg_regexp_k93 {
  print "
Program: regexp_k93

Convert and translate regular expressions into Korn Shell
patterns.  Resulting patterns can be used with Korn Shell
built-in commands such as "if", "while", and "case", to
perform Pattern matching.

Usage: ${1##*/} [-?] [-vV] 'regexp|...'

    Where:
        -v = Verbose Mode
        -V = Very Verbose Mode

Example: regexp_k93 '^start.*end$'

Author: Dana French (dfrench@mtxia.com)
        Copyright 2006 by Dana French

\"AutoContent\" enabled
"
}
################################################################
####
#### Description:
####
#### The purpose of this function is to translate regular
#### expressions into korn shell patterns. The resultant korn
#### shell pattern can be captured and then used with korn
#### shell pattern matching functions.
####
#### Limited regular expression functionality at this point
#### It understands the following regular expression
#### metacharacters:
####
####     .      ^     $       [  ]       \
####    \.      ^$    \$      \[X\]      \\
####     *      \*    .*      [a-z]*     \.*
####     +      \+    .+      [a-z]+     \.+
####    \(string\)    \
####
#### Assumptions:
####
#### The regular expression is assumed to be the first
#### command line argument after any options specified.  It
#### is usually best to enclose the regular expression in
#### single quotes on the command line to ensure the shell
#### does not process any of the metacharacters.
####
#### Dependencies:
####
#### This function is self contained and is not dependent
#### upon any external programs, functions or scripts.
####
#### Products:
####
#### This function produces a korn shell pattern equivalent
#### of the regular expression specified on the command line.
#### The korn shell pattern is written to STDOUT.
####
#### Configured Usage:
####
#### Details:
####
################################################################
function regexp_k93 {
  typeset VERSION="1.0"
  typeset TRUE="0"
  typeset FALSE="1"
  typeset VERBOSE="${FALSE}"
  typeset VERYVERB="${FALSE}"

  while getopts ":vV" OPTION
  do
    case "${OPTION}" in
        'v') VERBOSE="${TRUE}";;
        'V') VERYVERB="${TRUE}";;
      [?:#]) print "Syntax: regexp_k93 'regexp'" && return 1 ;;
    esac
  done

  shift $(( ${OPTIND} - 1 ))

#### Retrieve the remainder of the command line arguments
#### assuming they are regular expressions.  Parse multiple
#### RE's separated with OR '|' symbols or AND '&' symbols
#### and store each RE in an array to be processed
#### individually.

  IFS="|"
  REGEXP="${*}"
  IFS=$' \t\n'
  LOOPRE="${REGEXP}|"
  LOOPRE="${LOOPRE//\&/|}"
  LOOPRE="${LOOPRE//\|\|/|}"

  CNT="0"
  while [[ "_${LOOPRE}" != "_" ]]
  do
      REARRAY[CNT++]="${LOOPRE%%\|*}"
      LOOPRE="${LOOPRE#*\|}"
  done

#### If no regular expressions were specified on the command
#### line, display an error message and return from this
#### function.

  trap "usagemsg_regexp_k93 ${0}" EXIT
  if [[ "_${REGEXP}" == "_" ]]
  then
      print -- "# ERROR: Regular expression not specified."
      return 2
  fi
  trap "-" EXIT

  (( VERYVERB == TRUE )) && set -x
  (( VERBOSE  == TRUE )) && print -u 2 "# Entering Function: ${0}"
  (( VERBOSE  == TRUE )) && print -u 2 "# Version..........: ${VERSION}"

################################################################
#### Convert regular expression metacharacters to strings :

  for REGEXP in "${REARRAY[@]}"
  do

      (( VERBOSE  == TRUE )) && print -u 2 "# Specified regexp.: '${REGEXP}'"

#### convert '\' -> 'ESC' :
      REGEXP="${REGEXP//\\/%K93ESC%}"

#### convert '\$' -> '\$' :
      REGEXP="${REGEXP//%K93ESC%'$'/%K93ESC%%K93DOL%}"

#### convert 'beginning of line' -> 'BEG' :
      REGEXP="${REGEXP/#\^/%K93BEG%}"

#### convert 'end of line' -> 'END' :
      REGEXP="${REGEXP/%\$/%K93END%}"

#### convert '$' -> '$' :
      REGEXP="${REGEXP//'$'/%K93DOL%}"

#### convert '.' -> 'DOT' :
      REGEXP="${REGEXP//./%K93DOT%}"

#### convert '*' -> 'AST' :
      REGEXP="${REGEXP//\*/%K93AST%}"

#### convert '+' -> 'PLU' :
      REGEXP="${REGEXP//+/%K93PLU%}"

#### convert '<' -> 'LES' :
      REGEXP="${REGEXP//\' -> 'GRE' :
      REGEXP="${REGEXP//\>/%K93GRE%}"

#### convert '[' -> 'OSB' :
      REGEXP="${REGEXP//\[/%K93OSB%}"

#### convert ']' -> 'CSB' :
      REGEXP="${REGEXP//\]/%K93CSB%}"

#### convert '(' -> 'OPA' :
      REGEXP="${REGEXP//\(/%K93OPA%}"

#### convert ')' -> 'CPA' :
      REGEXP="${REGEXP//\)/%K93CPA%}"

#### convert '?' -> 'QUE' :
      REGEXP="${REGEXP//\?/%K93QUE%}"

#### convert '[^' -> '[!' :
      REGEXP="${REGEXP//%K93OSB%^/%K93OSB%%K93EXC%}"

#### convert 'regexp' -> '*regexp' :
      [[ "_${REGEXP}" != _%K93BEG%* ]] && REGEXP="%K93ANY%${REGEXP}"

#### convert 'regexp' -> 'regexp*' :
      [[ "_${REGEXP}" != _*%K93END% ]] && REGEXP="${REGEXP}%K93ANY%"

################################################################
#### Convert strings to korn shell patterns :

#### translate '^*' -> '*' :
      REGEXP="${REGEXP/#%K93ANY%/*}"

#### translate '*$' -> '*' :
      REGEXP="${REGEXP/%%K93ANY%/*}"

#### translate '\\*' -> '*(\\)' :
      REGEXP="${REGEXP//%K93ESC%%K93ESC%%K93AST%/*(\\)}"

#### translate '\\+' -> '+(\\)' :
      REGEXP="${REGEXP//%K93ESC%%K93ESC%%K93PLU%/+(\\)}"

#### translate '\**' -> '*(\*)' :
      REGEXP="${REGEXP//%K93ESC%%K93AST%%K93AST%/*(\*)}"

#### translate '\*+' -> '+(\*)' :
      REGEXP="${REGEXP//%K93ESC%%K93AST%%K93PLU%/+(\*)}"

#### translate '\^*' -> '*(^)' :
      REGEXP="${REGEXP//%K93ESC%%K93CAR%%K93AST%/*(^)}"

#### translate '\^+' -> '+(^)' :
      REGEXP="${REGEXP//%K93ESC%%K93CAR%%K93PLU%/+(^)}"

#### translate '\\' -> '\\' :
      REGEXP="${REGEXP//%K93ESC%%K93ESC%/\\\\}"

#### translate '\.*' -> '*(.)' :
      REGEXP="${REGEXP//%K93ESC%%K93DOT%%K93AST%/*(.)}"

#### translate '.*' -> '*(?)' :
      REGEXP="${REGEXP//%K93DOT%%K93AST%/*(?)}"

#### translate '\.+' -> '+(.)' :
      REGEXP="${REGEXP//%K93ESC%%K93DOT%%K93PLU%/+(.)}"

#### translate '.+' -> '+(?)' :
      REGEXP="${REGEXP//%K93DOT%%K93PLU%/+(?)}"

#### translate '\$*' -> '*(\$)' :
      REGEXP="${REGEXP//%K93ESC%%K93DOL%%K93AST%/*(\\$)}"

#### translate '\$+' -> '+(\$)' :
      REGEXP="${REGEXP//%K93ESC%%K93DOL%%K93PLU%/+(\\$)}"

#### translate '$*' -> '*(\$)' :
      REGEXP="${REGEXP//%K93DOL%%K93AST%/*('\$')}"

#### translate '$+' -> '+(\$)' :
      REGEXP="${REGEXP//%K93DOL%%K93PLU%/+(\\$)}"



#### translate '\[*' -> '*(\[)' :
      REGEXP="${REGEXP//%K93ESC%%K93OSB%%K93AST%/*(\\'[')}"

#### translate '\[+' -> '+(\[)' :
      REGEXP="${REGEXP//%K93ESC%%K93OSB%%K93PLU%/+(\\'[')}"

#### translate '\]*' -> '*(\])' :
      REGEXP="${REGEXP//%K93ESC%%K93CSB%%K93AST%/*(\\']')}"

#### translate '\]+' -> '+(\])' :
      REGEXP="${REGEXP//%K93ESC%%K93CSB%%K93PLU%/+(\\']')}"



#### translate '\*' -> '*(+([$' \t\n.,:'])string+([$' \t\n.,:']))'
      REGEXP="${REGEXP//%K93ESC%%K93LES%(*(?))%K93ESC%%K93GRE%%K93AST%/*([\$\' \\t\\n.,:\']\1[\$\' \\t\\n.,:\'])}"

#### translate '\' -> '+([$' \t\n.,:'])string+([$' \t\n.,:'])'
      REGEXP="${REGEXP//%K93ESC%%K93LES%(*(?))%K93ESC%%K93GRE%/[\$\' \\t\\n.,:\']\1[\$\' \\t\\n.,:\']}"

#### translate '<*' -> '*(\<)' :
      REGEXP="${REGEXP//%K93LES%%K93AST%/*(\\<)}"

#### translate '<+' -> '+(\<)' :
      REGEXP="${REGEXP//%K93LES%%K93PLU%/+(\\<)}"

#### translate '>*' -> '*(\>)' :
      REGEXP="${REGEXP//%K93GRE%%K93AST%/*(\\>)}"

#### translate '>+' -> '+(\>)' :
      REGEXP="${REGEXP//%K93GRE%%K93PLU%/+(\\>)}"



#### translate '\(string\)*' -> '*(\1)'
      REGEXP="${REGEXP//%K93ESC%%K93OPA%(*(?))%K93ESC%%K93CPA%%K93AST%/'*('\1')'}"

#### translate '\(string\)' -> '(\1)'
      REGEXP="${REGEXP//%K93ESC%%K93OPA%(*(?))%K93ESC%%K93CPA%/'('\1')'}"



#### translate '\(*' -> '*(\()' :
      REGEXP="${REGEXP//%K93ESC%%K93OPA%%K93AST%/*(\\'(')}"

#### translate '\(+' -> '+(\()' :
      REGEXP="${REGEXP//%K93ESC%%K93OPA%%K93PLU%/+(\\'(')}"

#### translate '\)*' -> '*(\))' :
      REGEXP="${REGEXP//%K93ESC%%K93CPA%%K93AST%/*(\\')')}"

#### translate '\)+' -> '+(\))' :
      REGEXP="${REGEXP//%K93ESC%%K93CPA%%K93PLU%/+(\\')')}"



#### translate '(*' -> '*(\()' :
      REGEXP="${REGEXP//%K93OPA%%K93AST%/*(\\'(')}"

#### translate '(+' -> '+(\()' :
      REGEXP="${REGEXP//%K93OPA%%K93PLU%/+(\\'(')}"

#### translate ')*' -> '*(\))' :
      REGEXP="${REGEXP//%K93CPA%%K93AST%/*(\\')')}"

#### translate ')+' -> '+(\))' :
      REGEXP="${REGEXP//%K93CPA%%K93PLU%/+(\\')')}"



#### translate '\X*' -> '*(X)' :
      REGEXP="${REGEXP//%K93ESC%(?)%K93AST%/*(\\\1)}"

#### translate '\X+' -> '+(X)' :
      REGEXP="${REGEXP//%K93ESC%(?)%K93PLU%/+(\\\1)}"

#### translate '[a-z]*' -> '*([a-z])' :
      REGEXP="${REGEXP//%K93OSB%(*(?))%K93CSB%%K93AST%/'*(['\1'])'}"

#### translate '[a-z]+' -> '+([a-z])' :
      REGEXP="${REGEXP//%K93OSB%(*(?))%K93CSB%%K93PLU%/'+(['\1'])'}"

#### translate '\*' -> '\*)' :
      REGEXP="${REGEXP//%K93ESC%%K93AST%/\\*}"

#### translate '\+' -> '\+)' :
      REGEXP="${REGEXP//%K93ESC%%K93PLU%/\\+}"

#### translate '\.' -> '.' :
      REGEXP="${REGEXP//%K93ESC%%K93DOT%/.}"

#### translate '^*' -> '\*' :
      REGEXP="${REGEXP/#%K93BEG%%K93AST%/\\*}"

#### translate '*$' -> '\*' :
      REGEXP="${REGEXP/%%K93AST%%K93END%/\\*}"

#### translate 'X*' -> '*(X)' :
      REGEXP="${REGEXP//(?)%K93AST%/*(\1)}"

#### translate 'X+' -> '+(X)' :
      REGEXP="${REGEXP//(?)%K93PLU%/+(\1)}"

#### translate '\^' -> '^' :
      REGEXP="${REGEXP//%K93ESC%%K93CAR%/\^}"

#### translate '\$' -> '\$' :
      REGEXP="${REGEXP//%K93ESC%%K93DOL%/\\$}"

#### translate '\[' -> '[' :
      REGEXP="${REGEXP//%K93ESC%%K93OSB%/'\['}"

#### translate '\]' -> ']' :
      REGEXP="${REGEXP//%K93ESC%%K93CSB%/'\]'}"

#### translate '[^' -> '[!' :
      REGEXP="${REGEXP//%K93OSB%%K93EXC%/'['!}"

#### translate 'LES' -> '<' :
      REGEXP="${REGEXP//%K93LES%/'\<'}"

#### translate 'GRE' -> '>' :
      REGEXP="${REGEXP//%K93GRE%/'\>'}"

#### translate 'OSB' -> '[' :
      REGEXP="${REGEXP//%K93OSB%/'['}"

#### translate 'CSB' -> ']' :
      REGEXP="${REGEXP//%K93CSB%/']'}"

#### translate 'OPA' -> '(' :
      REGEXP="${REGEXP//%K93OPA%/'\('}"

#### translate 'CPA' -> ')' :
      REGEXP="${REGEXP//%K93CPA%/'\)'}"

#### translate 'DOT' -> '?' :
      REGEXP="${REGEXP//%K93DOT%/?}"

#### translate 'CAR' -> '^' :
      REGEXP="${REGEXP//%K93CAR%/^}"

#### translate 'EXC' -> '!' :
      REGEXP="${REGEXP//%K93EXC%/!}"

#### translate 'AST' -> '*' :
      REGEXP="${REGEXP//%K93AST%/*}"

#### translate 'PLU' -> '+' :
      REGEXP="${REGEXP//%K93PLU%/+}"

#### translate 'QUE' -> '?' :
      REGEXP="${REGEXP//%K93QUE%/\?}"

#### translate 'ESC' -> '\' :
      REGEXP="${REGEXP//%K93ESC%/\\}"

#### translate 'DOL' -> '\$' :
      REGEXP="${REGEXP//%K93DOL%/\\$}"

#### translate 'beginning of line' -> '' :
      REGEXP="${REGEXP/#%K93BEG%/}"

#### translate 'end of line' -> '' :
      REGEXP="${REGEXP/%%K93END%/}"

      print -r -- "${REGEXP}"
      (( VERBOSE  == TRUE )) && print -u 2 "# Resultant Pattern: '${REGEXP}'"
  done

  (( VERBOSE  == TRUE )) && print -u 2 "# Exiting Function.: ${0}"
  return 0
}
################################################################

regexp_k93 "${@}"