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PROLOG

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

NAME

       echo — write arguments to standard output

SYNOPSIS

       echo [string...]

DESCRIPTION

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

OPTIONS

       The echo utility shall not  recognize  the  "−−"  argument  in  the  manner  specified  by
       Guideline  10 of the Base Definitions volume of POSIX.1‐2008, Section 12.2, Utility Syntax
       Guidelines; "−−" shall be recognized as a string operand.

       Implementations shall not support any options.

OPERANDS

       The following operands shall be supported:

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

                 On XSI-conformant systems, if the first operand is −n, 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  '\c' 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.

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

STDIN

       Not used.

INPUT FILES

       None.

ENVIRONMENT VARIABLES

       The following environment variables shall affect the execution of echo:

       LANG      Provide a default value for the internationalization variables that are unset or
                 null.  (See  the  Base  Definitions  volume  of   POSIX.1‐2008,   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).

       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.

ASYNCHRONOUS EVENTS

       Default.

STDOUT

       The echo 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.

STDERR

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES

       None.

EXTENDED DESCRIPTION

       None.

EXIT STATUS

       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.

CONSEQUENCES OF ERRORS

       Default.

       The following sections are informative.

APPLICATION USAGE

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

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

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

               printf "%b\n$*"

        *  The BSD echo is equivalent to:

               if [ "X$1" = "X−n" ]
               then
                   shift
                   printf "%s$*"
               else
                   printf "%s\n$*"
               fi

       New applications are encouraged to use printf instead of echo.

EXAMPLES

       None.

RATIONALE

       The  echo 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 −n, should use the
       printf utility derived from the Ninth Edition system.

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

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

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

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

FUTURE DIRECTIONS

       None.

SEE ALSO

       printf

       The  Base  Definitions  volume  of POSIX.1‐2008, Chapter 8, Environment Variables, Section
       12.2, Utility Syntax Guidelines

COPYRIGHT

       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 .