UnixReview.com
June 2006

Listing 6: lcase.c

/* lcase - convert string to lowercase */

#include <config.h>

#if defined (HAVE_UNISTD_H)
#  include <unistd.h>
#endif
#include "bashansi.h"
#include <stdio.h>
#include <errno.h>

#include "builtins.h"
#include "shell.h"
#include "bashgetopt.h"

#if !defined (errno)
extern int errno;
#endif

extern char *strerror ();

lcase_builtin (list)
     WORD_LIST *list;
{
  int n = 0;
  int ch;
  char *string;
  char *var = NULL;

  reset_internal_getopt ();
  while ((ch = internal_getopt (list, "p:")) != -1)
    switch(ch) {
      case 'p':
        var = list_optarg;
        break;
      default:
        builtin_usage();
        return (EX_USAGE);
    }
  list = loptend;

  if (list == 0 || list->next)
    {
      builtin_usage ();
      return (EX_USAGE);
    }

  if (no_options (list))
    return (EX_USAGE);

  string = list->word->word;

  while ( string[n] )
    {
      string[n] = tolower(string[n]);
      ++n;
    }

  if ( var )
    bind_variable (var, string, 0);
  else
    printf ("%s\n", string);

  return (EXECUTION_SUCCESS);
}

char *lcase_doc[] = {
	"The STRING is converted to lower case and either:",
        "    stored in the variable supplied with -p",
        "  or",
        "    printed to stdout if no variable is given",
	(char *)NULL
};

struct builtin lcase_struct = {
	"lcase",		/* builtin name */
	lcase_builtin,	/* function implementing the builtin */
	BUILTIN_ENABLED,	/* initial flags for builtin */
	lcase_doc,		/* array of long documentation strings. */
	"lcase [-p VAR] STRING",	/* usage synopsis */
	0			/* reserved for internal use */
};