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ECHO(P)			   POSIX Programmer's Manual		       ECHO(P)

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
       IEEE Std 1003.1-2001, 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 argu‐
       ments:

       \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 argu‐
	      ments 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
	      IEEE Std 1003.1-2001,  Section  8.2,  Internationalization Vari‐
	      ables 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>s and  a
       <newline>  shall	 follow	 the  last argument.	Output transformations
       shall occur based on the escape sequences in the input. See  the	 OPER‐
       ANDS 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	tradi‐
       tional  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  implementa‐
	  tions in this volume of IEEE Std 1003.1-2001 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>s 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

COPYRIGHT
       Portions	 of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating	System	Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003	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 .

IEEE/The Open Group		     2003			       ECHO(P)
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