GETOPTS(1P)						     POSIX Programmer's Manual						       GETOPTS(1P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       getopts - parse utility options

SYNOPSIS

       getopts optstring name [arg...]

DESCRIPTION

       The getopts utility shall retrieve options and option-arguments from a list of parameters. It shall support the Utility Syntax Guidelines 3
       to 10, inclusive, described in the Base Definitions volume of IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.

       Each  time  it is invoked, the getopts utility shall place the value of the next option in the shell variable specified by the name operand
       and the index of the next argument to be processed in the shell variable OPTIND.  Whenever the shell is invoked, OPTIND shall  be  initial-
       ized to 1.

       When  the  option requires an option-argument, the getopts utility shall place it in the shell variable OPTARG.	If no option was found, or
       if the option that was found does not have an option-argument, OPTARG shall be unset.

       If an option character not contained in the optstring operand is found where an option character is expected, the shell variable  specified
       by  name  shall	be  set  to the question-mark ( '?' ) character. In this case, if the first character in optstring is a colon ( ':' ), the
       shell variable OPTARG shall be set to the option character found, but no output shall be written to standard error;  otherwise,	the  shell
       variable  OPTARG  shall	be  unset and a diagnostic message shall be written to standard error. This condition shall be considered to be an
       error detected in the way arguments were presented to the invoking application, but shall not be an error in getopts processing.

       If an option-argument is missing:

	* If the first character of optstring is a colon, the shell variable specified by name shall be set to the colon character and	the  shell
	  variable OPTARG shall be set to the option character found.

	* Otherwise,  the  shell variable specified by name shall be set to the question-mark character, the shell variable OPTARG shall be unset,
	  and a diagnostic message shall be written to standard error. This condition shall be considered to be an error detected in the way argu-
	  ments were presented to the invoking application, but shall not be an error in getopts processing; a diagnostic message shall be written
	  as stated, but the exit status shall be zero.

       When the end of options is encountered, the getopts utility shall exit with a return value greater than zero;  the  shell  variable  OPTIND
       shall  be  set to the index of the first non-option-argument, where the first "--" argument is considered to be an option-argument if there
       are no other non-option-arguments appearing before it, or the value "$#" +1 if there are no non-option-arguments; the name  variable  shall
       be set to the question-mark character. Any of the following shall identify the end of options: the special option "--", finding an argument
       that does not begin with a '-', or encountering an error.

       The shell variables OPTIND and OPTARG shall be local to the caller of getopts and shall not be exported by default.

       The shell variable specified by the name operand, OPTIND , and OPTARG shall affect the current shell execution environment; see Shell  Exe-
       cution Environment .

       If  the	application  sets  OPTIND to the value 1, a new set of parameters can be used: either the current positional parameters or new arg
       values. Any other attempt to invoke getopts multiple times in a single shell execution environment with parameters  (positional	parameters
       or  arg	operands) that are not the same in all invocations, or with an OPTIND value modified to be a value other than 1, produces unspeci-
       fied results.

OPTIONS

       None.

OPERANDS

       The following operands shall be supported:

       optstring
	      A string containing the option characters recognized by the utility invoking getopts. If a character is followed	by  a  colon,  the
	      option shall be expected to have an argument, which should be supplied as a separate argument. Applications should specify an option
	      character and its option-argument as separate arguments, but getopts shall interpret the characters following  an  option  character
	      requiring arguments as an argument whether or not this is done. An explicit null option-argument need not be recognized if it is not
	      supplied as a separate argument when getopts is invoked. (See also the getopt() function defined in the System Interfaces volume	of
	      IEEE Std 1003.1-2001.)   The characters question-mark and colon shall not be used as option characters by an application. The use of
	      other option characters that are not alphanumeric produces unspecified results. If the option-argument is not supplied as a separate
	      argument	from the option character, the value in OPTARG shall be stripped of the option character and the '-' . The first character
	      in optstring determines how getopts behaves if an option character is not known or an option-argument is missing.

       name   The name of a shell variable that shall be set by the getopts utility to the option character that was found.

       The getopts utility by default shall parse positional parameters passed to the invoking shell procedure. If args are given, they  shall	be
       parsed instead of the positional parameters.

STDIN

       Not used.

INPUT FILES

       None.

ENVIRONMENT VARIABLES

       The following environment variables shall affect the execution of getopts:

       LANG   Provide  a  default  value  for  the  internationalization  variables  that  are	unset or null. (See the Base Definitions volume of
	      IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for the  precedence  of  internationalization  variables  used	to
	      determine the values of locale categories.)

       LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables.

       LC_CTYPE
	      Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to
	      multi-byte characters in arguments and input files).

       LC_MESSAGES
	      Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.

       NLSPATH
	      Determine the location of message catalogs for the processing of LC_MESSAGES .

       OPTIND This variable shall be used by the getopts utility as the index of the next argument to be processed.

ASYNCHRONOUS EVENTS

       Default.

STDOUT

       Not used.

STDERR

       Whenever an error is detected and the first character in the optstring operand is not a colon ( ':' ), a diagnostic message shall be  writ-
       ten to standard error with the following information in an unspecified format:

	* The  invoking program name shall be identified in the message. The invoking program name shall be the value of the shell special parame-
	  ter 0 (see Special Parameters ) at the time the getopts utility is invoked. A name equivalent to:

	  basename "$0"

       may be used.

	* If an option is found that was not specified in optstring, this error is identified and the invalid option character shall be identified
	  in the message.

	* If  an option requiring an option-argument is found, but an option-argument is not found, this error shall be identified and the invalid
	  option character shall be identified in the message.

OUTPUT FILES

       None.

EXTENDED DESCRIPTION

       None.

EXIT STATUS

       The following exit values shall be returned:

	0     An option, specified or unspecified by optstring, was found.

       >0     The end of options was encountered or an error occurred.

CONSEQUENCES OF ERRORS

       Default.

       The following sections are informative.

APPLICATION USAGE

       Since getopts affects the current shell execution environment, it is generally provided as a shell regular built-in. If it is called  in  a
       subshell or separate utility execution environment, such as one of the following:

	      (getopts abc value "$@")
	      nohup getopts ...
	      find . -exec getopts ... ;

       it does not affect the shell variables in the caller's environment.

       Note  that  shell functions share OPTIND with the calling shell even though the positional parameters are changed. If the calling shell and
       any of its functions uses getopts to parse arguments, the results are unspecified.

EXAMPLES

       The following example script parses and displays its arguments:

	      aflag=
	      bflag=
	      while getopts ab: name
	      do
		  case $name in
		  a)	aflag=1;;
		  b)	bflag=1
			bval="$OPTARG";;
		  ?)	printf "Usage: %s: [-a] [-b value] args
" $0
			exit 2;;
		  esac
	      done
	      if [ ! -z "$aflag" ]; then
		  printf "Option -a specified
"
	      fi
	      if [ ! -z "$bflag" ]; then
		  printf 'Option -b "%s" specified
' "$bval"
	      fi
	      shift $(($OPTIND - 1))
	      printf "Remaining arguments are: %s
" "$*"

RATIONALE

       The getopts utility was chosen in preference to the System V getopt utility because getopts handles option-arguments containing <blank>s.

       The OPTARG variable is not mentioned in the ENVIRONMENT VARIABLES section because it does not affect the execution of getopts; it is one of
       the few "output-only" variables used by the standard utilities.

       The colon is not allowed as an option character because that is not historical behavior, and it violates the Utility Syntax Guidelines. The
       colon is now specified to behave as in the KornShell version of the getopts utility; when used as the first character in the optstring  op-
       erand,  it  disables  diagnostics concerning missing option-arguments and unexpected option characters. This replaces the use of the OPTERR
       variable that was specified in an early proposal.

       The formats of the diagnostic messages produced by the getopts utility and the getopt() function are not fully specified because  implemen-
       tations with superior (``friendlier") formats objected to the formats used by some historical implementations. The standard developers con-
       sidered it important that the information in the messages used be uniform between getopts and getopt(). Exact duplication of  the  messages
       might  not  be possible, particularly if a utility is built on another system that has a different getopt() function, but the messages must
       have specific information included so that the program name, invalid option character, and type of error can be distinguished by a user.

       Only a rare application program intercepts a getopts standard error message and wants to parse it. Therefore, implementations are  free	to
       choose the most usable messages they can devise. The following formats are used by many historical implementations:

	      "%s: illegal option -- %c
", <program name>, <option character>

	      "%s: option requires an argument -- %c
", <program name>, 
		  <option character>

       Historical  shells  with  built-in  versions  of getopt() or getopts have used different formats, frequently not even indicating the option
       character found in error.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Special Parameters, the System Interfaces volume of IEEE Std 1003.1-2001, getopt()

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and  the  original  IEEE
       and  The  Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003							       GETOPTS(1P)