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



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

NNAAMMEE
       getopts -- parse utility options

SSYYNNOOPPSSIISS
       getopts _o_p_t_s_t_r_i_n_g _n_a_m_e [[_a_r_g...]]

DDEESSCCRRIIPPTTIIOONN
       The _g_e_t_o_p_t_s 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
       POSIX.1-2017, _S_e_c_t_i_o_n _1_2_._2, _U_t_i_l_i_t_y _S_y_n_t_a_x _G_u_i_d_e_l_i_n_e_s.

       Each time it is invoked, the _g_e_t_o_p_t_s utility shall place the value of
       the next option in the shell variable specified by the _n_a_m_e operand and
       the index of the next argument to be processed in the shell variable
       _O_P_T_I_N_D.  Whenever the shell is invoked, _O_P_T_I_N_D shall be initialized to
       1.

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

       If an option character not contained in the _o_p_t_s_t_r_i_n_g operand is found
       where an option character is expected, the shell variable specified by
       _n_a_m_e shall be set to the <question-mark> (''??'')  character. In this
       case, if the first character in _o_p_t_s_t_r_i_n_g is a <colon> (''::''), the shell
       variable _O_P_T_A_R_G shall be set to the option character found, but no
       output shall be written to standard error; otherwise, the shell
       variable _O_P_T_A_R_G 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 _g_e_t_o_p_t_s processing.

       If an option-argument is missing:

        *  If the first character of _o_p_t_s_t_r_i_n_g is a <colon>, the shell
           variable specified by _n_a_m_e shall be set to the <colon> character
           and the shell variable _O_P_T_A_R_G shall be set to the option character
           found.

        *  Otherwise, the shell variable specified by _n_a_m_e shall be set to the
           <question-mark> character, the shell variable _O_P_T_A_R_G 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 _g_e_t_o_p_t_s processing; a diagnostic message shall
           be written as stated, but the exit status shall be zero.

       When the end of options is encountered, the _g_e_t_o_p_t_s utility shall exit
       with a return value greater than zero; the shell variable _O_P_T_I_N_D shall
       be set to the index of the first operand, or the value ""$$##""+1 if there
       are no operands; the _n_a_m_e variable shall be set to the <question-mark>
       character. Any of the following shall identify the end of options: the
       first ""----"" argument that is not an option-argument, finding an argument
       that is not an option-argument and does not begin with a ''--'', or
       encountering an error.

       The shell variables _O_P_T_I_N_D and _O_P_T_A_R_G shall be local to the caller of
       _g_e_t_o_p_t_s and shall not be exported by default.

       The shell variable specified by the _n_a_m_e operand, _O_P_T_I_N_D, and _O_P_T_A_R_G
       shall affect the current shell execution environment; see _S_e_c_t_i_o_n _2_._1_2,
       _S_h_e_l_l _E_x_e_c_u_t_i_o_n _E_n_v_i_r_o_n_m_e_n_t.

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

OOPPTTIIOONNSS
       None.

OOPPEERRAANNDDSS
       The following operands shall be supported:

       _o_p_t_s_t_r_i_n_g A string containing the option characters recognized by the
                 utility invoking _g_e_t_o_p_t_s.  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 _g_e_t_o_p_t_s 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 _g_e_t_o_p_t_s is invoked. (See also the
                 _g_e_t_o_p_t() function defined in the System Interfaces volume of
                 POSIX.1-2017.) 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 _O_P_T_A_R_G shall be stripped of the option character
                 and the ''--''.  The first character in _o_p_t_s_t_r_i_n_g determines how
                 _g_e_t_o_p_t_s behaves if an option character is not known or an
                 option-argument is missing.

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

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

SSTTDDIINN
       Not used.

IINNPPUUTT FFIILLEESS
       None.

EENNVVIIRROONNMMEENNTT VVAARRIIAABBLLEESS
       The following environment variables shall affect the execution of
       _g_e_t_o_p_t_s:

       _L_A_N_G      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base Definitions
                 volume of POSIX.1-2017, _S_e_c_t_i_o_n _8_._2, _I_n_t_e_r_n_a_t_i_o_n_a_l_i_z_a_t_i_o_n
                 _V_a_r_i_a_b_l_e_s for the precedence of internationalization
                 variables used to determine the values of locale categories.)

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

       _L_C___C_T_Y_P_E  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).

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

       _N_L_S_P_A_T_H   Determine the location of message catalogs for the processing
                 of _L_C___M_E_S_S_A_G_E_S.

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

AASSYYNNCCHHRROONNOOUUSS EEVVEENNTTSS
       Default.

SSTTDDOOUUTT
       Not used.

SSTTDDEERRRR
       Whenever an error is detected and the first character in the _o_p_t_s_t_r_i_n_g
       operand is not a <colon> (''::''), a diagnostic message shall be written
       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
           parameter 0 (see _S_e_c_t_i_o_n _2_._5_._2, _S_p_e_c_i_a_l _P_a_r_a_m_e_t_e_r_s) at the time the
           _g_e_t_o_p_t_s utility is invoked. A name equivalent to:


               basename "$0"

           may be used.

        *  If an option is found that was not specified in _o_p_t_s_t_r_i_n_g, 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.

OOUUTTPPUUTT FFIILLEESS
       None.

EEXXTTEENNDDEEDD DDEESSCCRRIIPPTTIIOONN
       None.

EEXXIITT SSTTAATTUUSS
       The following exit values shall be returned:

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

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

CCOONNSSEEQQUUEENNCCEESS OOFF EERRRROORRSS
       Default.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       Since _g_e_t_o_p_t_s 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 _O_P_T_I_N_D with the calling shell even
       though the positional parameters are changed. If the calling shell and
       any of its functions uses _g_e_t_o_p_t_s to parse arguments, the results are
       unspecified.

EEXXAAMMPPLLEESS
       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\n" $0
                     exit 2;;
               esac
           done
           if [ ! -z "$aflag" ]; then
               printf "Option -a specified\n"
           fi
           if [ ! -z "$bflag" ]; then
               printf 'Option -b "%s" specified\n' "$bval"
           fi
           shift $(($OPTIND - 1))
           printf "Remaining arguments are: %s\n$*"

RRAATTIIOONNAALLEE
       The _g_e_t_o_p_t_s utility was chosen in preference to the System V _g_e_t_o_p_t
       utility because _g_e_t_o_p_t_s handles option-arguments containing <blank>
       characters.

       The _O_P_T_A_R_G variable is not mentioned in the ENVIRONMENT VARIABLES
       section because it does not affect the execution of _g_e_t_o_p_t_s; 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
       _g_e_t_o_p_t_s utility; when used as the first character in the _o_p_t_s_t_r_i_n_g
       operand, it disables diagnostics concerning missing option-arguments
       and unexpected option characters. This replaces the use of the _O_P_T_E_R_R
       variable that was specified in an early proposal.

       The formats of the diagnostic messages produced by the _g_e_t_o_p_t_s utility
       and the _g_e_t_o_p_t() function are not fully specified because
       implementations with superior (``friendlier'') formats objected to the
       formats used by some historical implementations. The standard
       developers considered it important that the information in the messages
       used be uniform between _g_e_t_o_p_t_s and _g_e_t_o_p_t().  Exact duplication of the
       messages might not be possible, particularly if a utility is built on
       another system that has a different _g_e_t_o_p_t() 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 _g_e_t_o_p_t_s 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\n", <_p_r_o_g_r_a_m _n_a_m_e>, <_o_p_t_i_o_n _c_h_a_r_a_c_t_e_r>

           "%s: option requires an argument -- %c\n", <_p_r_o_g_r_a_m _n_a_m_e>, \
               <_o_p_t_i_o_n _c_h_a_r_a_c_t_e_r>

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

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _S_e_c_t_i_o_n _2_._5_._2, _S_p_e_c_i_a_l _P_a_r_a_m_e_t_e_r_s

       The Base Definitions volume of POSIX.1-2017, _C_h_a_p_t_e_r _8, _E_n_v_i_r_o_n_m_e_n_t
       _V_a_r_i_a_b_l_e_s, _S_e_c_t_i_o_n _1_2_._2, _U_t_i_l_i_t_y _S_y_n_t_a_x _G_u_i_d_e_l_i_n_e_s

       The System Interfaces volume of POSIX.1-2017, _g_e_t_o_p_t()

CCOOPPYYRRIIGGHHTT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                           GETOPTS(1)
