UnixReview.com
June 2006

Listing 5: newbi-sh

#! /bin/bash

#@ If no name is given on the command line, prompt the user for it
if [ -n "$1" ]
then
  builtin=$1
else
  read -ep "Name of builtin: " builtin
  [ -z "$builtin" ] && exit 1
fi

#@ If a C file for the builtin exists, ask whether to overwrite it
if [ -s "$builtin.c" ]
then
  ls -l "$builtin.c"
  read -sn1 -p "Overwrite $builtin.c [y/N/c]? " ok
  case $X in
      [yY]) ;;
      [cC]) exit 2 ;;
      * ) ok= ;;
  esac
  printf "\n"
else
  ok=1
fi

#@ Use template.c as the basis for the new builtin
if [ -n "$ok" ]
then
  sed "s/template/$builtin/g" template.c > "$builtin.c"
fi

#@ Make a copy of the existing makefile
cp Makefile mkf || exit 2

{
#@ Add the new builtin to Makefile
#@ [should add check to see if it's already there]
    fmt="\t\$(SHOBJ_LD) \$(SHOBJ_LDFLAGS) \$(SHOBJ_XLDFLAGS)"
    fmt="$fmt -o \$@ %s.o \$(SHOBJ_LIBS)\n"
    sed "/^all:/ s/\$/ $builtin/" mkf
    printf "\n%s: %s.o\n" "$builtin" "$builtin"
    printf "$fmt" "$builtin"
    printf "\n%s.c: %s.o\n" "$builtin" "$builtin"
} > Makefile