ECHO(1)                    POSIX Programmer's Manual                   ECHO(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
       echo -- write arguments to standard output

SSYYNNOOPPSSIISS
       echo [[_s_t_r_i_n_g...]]

DDEESSCCRRIIPPTTIIOONN
       The _e_c_h_o utility writes its arguments to standard output, followed by a
       <newline>.  If there are no arguments, only the <newline> is written.

OOPPTTIIOONNSS
       The _e_c_h_o utility shall not recognize the ""----"" argument in the manner
       specified by Guideline 10 of the Base Definitions volume of
       POSIX.1-2008, _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; ""----"" shall be
       recognized as a string operand.

       Implementations shall not support any options.

OOPPEERRAANNDDSS
       The following operands shall be supported:

       _s_t_r_i_n_g    A string to be written to standard output. If the first
                 operand is --nn, or if any of the operands contain a
                 <backslash> character, the results are implementation-
                 defined.

                 On XSI-conformant systems, if the first operand is --nn, it
                 shall be treated as a string, not an option. The following
                 character sequences shall be recognized on XSI-conformant
                 systems within any of the arguments:

                 \a      Write an <alert>.

                 \b      Write a <backspace>.

                 \c      Suppress the <newline> that otherwise follows the
                         final argument in the output. All characters
                         following the ''\\cc'' in the arguments shall be ignored.

                 \f      Write a <form-feed>.

                 \n      Write a <newline>.

                 \r      Write a <carriage-return>.

                 \t      Write a <tab>.

                 \v      Write a <vertical-tab>.

                 \\      Write a <backslash> character.

                 \0_n_u_m   Write an 8-bit value that is the zero, one, two, or
                         three-digit octal number _n_u_m.

SSTTDDIINN
       Not used.

IINNPPUUTT FFIILLEESS
       None.

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

       _L_A_N_G      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base Definitions
                 volume of POSIX.1-2008, _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 _e_c_h_o utility arguments shall be separated by single <space>
       characters and a <newline> character shall follow the last argument.
       Output transformations shall occur based on the escape sequences in the
       input. See the OPERANDS section.

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
       It is not possible to use _e_c_h_o portably across all POSIX systems unless
       both --nn (as the first argument) and escape sequences are omitted.

       The _p_r_i_n_t_f utility can be used portably to emulate any of the
       traditional behaviors of the _e_c_h_o utility as follows (assuming that _I_F_S
       has its standard value or is unset):

        *  The historic System V _e_c_h_o and the requirements on XSI
           implementations in this volume of POSIX.1-2008 are equivalent to:

               pprriinnttff ""%%bb\\nn$$**""

        *  The BSD _e_c_h_o is equivalent to:

               iiff [[ ""XX$$11"" == ""XX--nn"" ]]
               tthheenn
                   sshhiifftt
                   pprriinnttff ""%%ss$$**""
               eellssee
                   pprriinnttff ""%%ss\\nn$$**""
               ffii

       New applications are encouraged to use _p_r_i_n_t_f instead of _e_c_h_o.

EEXXAAMMPPLLEESS
       None.

RRAATTIIOONNAALLEE
       The _e_c_h_o utility has not been made obsolescent because of its extremely
       widespread use in historical applications. Conforming applications that
       wish to do prompting without <newline> characters or that could
       possibly be expecting to echo a --nn, should use the _p_r_i_n_t_f utility
       derived from the Ninth Edition system.

       As specified, _e_c_h_o writes its arguments in the simplest of ways. The
       two different historical versions of _e_c_h_o vary in fatally incompatible
       ways.

       The BSD _e_c_h_o checks the first argument for the string --nn which causes
       it to suppress the <newline> that would otherwise follow the final
       argument in the output.

       The System V _e_c_h_o does not support any options, but allows escape
       sequences within its operands, as described for XSI implementations in
       the OPERANDS section.

       The _e_c_h_o utility does not support Utility Syntax Guideline 10 because
       historical applications depend on _e_c_h_o to echo _a_l_l of its arguments,
       except for the --nn option in the BSD version.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _p_r_i_n_t_f

       The Base Definitions volume of POSIX.1-2008, _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, 2013 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group.  (This is
       POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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                  2013                              ECHO(1)
