HASH(1)                    POSIX Programmer's Manual                   HASH(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
       hash -- remember or report utility locations

SSYYNNOOPPSSIISS
       hash [[_u_t_i_l_i_t_y...]]

       hash -r

DDEESSCCRRIIPPTTIIOONN
       The _h_a_s_h utility shall affect the way the current shell environment
       remembers the locations of utilities found as described in _S_e_c_t_i_o_n
       _2_._9_._1_._1, _C_o_m_m_a_n_d _S_e_a_r_c_h _a_n_d _E_x_e_c_u_t_i_o_n.  Depending on the arguments
       specified, it shall add utility locations to its list of remembered
       locations or it shall purge the contents of the list. When no arguments
       are specified, it shall report on the contents of the list.

       Utilities provided as built-ins to the shell shall not be reported by
       _h_a_s_h.

OOPPTTIIOONNSS
       The _h_a_s_h utility shall conform to 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.

       The following option shall be supported:

       --rr        Forget all previously remembered utility locations.

OOPPEERRAANNDDSS
       The following operand shall be supported:

       _u_t_i_l_i_t_y   The name of a utility to be searched for and added to the
                 list of remembered locations. If _u_t_i_l_i_t_y contains one or more
                 <slash> characters, the results are unspecified.

SSTTDDIINN
       Not used.

IINNPPUUTT FFIILLEESS
       None.

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

       _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).

       _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.

       _P_A_T_H      Determine the location of _u_t_i_l_i_t_y, as described in 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.

AASSYYNNCCHHRROONNOOUUSS EEVVEENNTTSS
       Default.

SSTTDDOOUUTT
       The standard output of _h_a_s_h shall be used when no arguments are
       specified. Its format is unspecified, but includes the pathname of each
       utility in the list of remembered locations for the current shell
       environment. This list shall consist of those utilities named in
       previous _h_a_s_h invocations that have been invoked, and may contain those
       invoked and found through the normal command search process.

SSTTDDEERRRR
       The standard error shall be used only for diagnostic messages.

OOUUTTPPUUTT FFIILLEESS
       None.

EEXXTTEENNDDEEDD DDEESSCCRRIIPPTTIIOONN
       None.

EEXXIITT SSTTAATTUUSS
       The following exit values shall be returned:

        0    Successful completion.

       >0    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 _h_a_s_h affects the current shell execution environment, it is
       always provided as a shell regular built-in. If it is called in a
       separate utility execution environment, such as one of the following:


           nohup hash -r
           find . -type f | xargs hash

       it does not affect the command search process of the caller's
       environment.

       The _h_a_s_h utility may be implemented as an alias--for example, _a_l_i_a_s
       --tt --, in which case utilities found through normal command search are
       not listed by the _h_a_s_h command.

       The effects of _h_a_s_h --rr can also be achieved portably by resetting the
       value of _P_A_T_H; in the simplest form, this can be:


           PATH="$PATH"

       The use of _h_a_s_h with _u_t_i_l_i_t_y names is unnecessary for most
       applications, but may provide a performance improvement on a few
       implementations; normally, the hashing process is included by default.

EEXXAAMMPPLLEESS
       None.

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _S_e_c_t_i_o_n _2_._9_._1_._1, _C_o_m_m_a_n_d _S_e_a_r_c_h _a_n_d _E_x_e_c_u_t_i_o_n

       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

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                              HASH(1)
