ALIAS(1)                   POSIX Programmer's Manual                  ALIAS(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
       alias -- define or display aliases

SSYYNNOOPPSSIISS
       alias [[_a_l_i_a_s_-_n_a_m_e[[=_s_t_r_i_n_g]]...]]

DDEESSCCRRIIPPTTIIOONN
       The _a_l_i_a_s utility shall create or redefine alias definitions or write
       the values of existing alias definitions to standard output. An alias
       definition provides a string value that shall replace a command name
       when it is encountered; see _S_e_c_t_i_o_n _2_._3_._1, _A_l_i_a_s _S_u_b_s_t_i_t_u_t_i_o_n.

       An alias definition shall affect the current shell execution
       environment and the execution environments of the subshells of the
       current shell. When used as specified by this volume of POSIX.1-2017,
       the alias definition shall not affect the parent process of the current
       shell nor any utility environment invoked by the shell; 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.

OOPPTTIIOONNSS
       None.

OOPPEERRAANNDDSS
       The following operands shall be supported:

       _a_l_i_a_s_-_n_a_m_e
                 Write the alias definition to standard output.

       _a_l_i_a_s_-_n_a_m_e=_s_t_r_i_n_g
                 Assign the value of _s_t_r_i_n_g to the alias _a_l_i_a_s_-_n_a_m_e.

       If no operands are given, all alias definitions shall be written to
       standard output.

SSTTDDIINN
       Not used.

IINNPPUUTT FFIILLEESS
       None.

EENNVVIIRROONNMMEENNTT VVAARRIIAABBLLEESS
       The following environment variables shall affect the execution of
       _a_l_i_a_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).

       _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.

AASSYYNNCCHHRROONNOOUUSS EEVVEENNTTSS
       Default.

SSTTDDOOUUTT
       The format for displaying aliases (when no operands or only _n_a_m_e
       operands are specified) shall be:


           "%s=%s\n", _n_a_m_e, _v_a_l_u_e

       The _v_a_l_u_e string shall be written with appropriate quoting so that it
       is suitable for reinput to the shell. See the description of shell
       quoting in _S_e_c_t_i_o_n _2_._2, _Q_u_o_t_i_n_g.

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    One of the _n_a_m_e operands specified did not have an alias
             definition, 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
       None.

EEXXAAMMPPLLEESS
        1. Create a short alias for a commonly used _l_s command:


               alias lf="ls -CF"

        2. Create a simple ``redo'' command to repeat previous entries in the
           command history file:


               alias r='fc -s'

        3. Use 1K units for _d_u:


               alias du=du\ -k

        4. Set up _n_o_h_u_p so that it can deal with an argument that is itself an
           alias name:


               alias nohup="nohup "

RRAATTIIOONNAALLEE
       The _a_l_i_a_s description is based on historical KornShell implementations.
       Known differences exist between that and the C shell. The KornShell
       version was adopted to be consistent with all the other KornShell
       features in this volume of POSIX.1-2017, such as command line editing.

       Since _a_l_i_a_s affects the current shell execution environment, it is
       generally provided as a shell regular built-in.

       Historical versions of the KornShell have allowed aliases to be
       exported to scripts that are invoked by the same shell. This is
       triggered by the _a_l_i_a_s --xx flag; it is allowed by this volume of
       POSIX.1-2017 only when an explicit extension such as --xx is used. The
       standard developers considered that aliases were of use primarily to
       interactive users and that they should normally not affect shell
       scripts called by those users; functions are available to such scripts.

       Historical versions of the KornShell had not written aliases in a
       quoted manner suitable for reentry to the shell, but this volume of
       POSIX.1-2017 has made this a requirement for all similar output.
       Therefore, consistency was chosen over this detail of historical
       practice.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _S_e_c_t_i_o_n _2_._9_._5, _F_u_n_c_t_i_o_n _D_e_f_i_n_i_t_i_o_n _C_o_m_m_a_n_d

       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

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                             ALIAS(1)
