NAME

       read - read a line from standard input

SYNOPSIS

       read [-r] var...

DESCRIPTION

       The read utility shall read a single line from standard input.

       By  default,  unless  the -r option is specified, backslash ( '\' ) shall act as an escape
       character, as described in Escape Character (Backslash) . If standard input is a  terminal
       device  and  the  invoking shell is interactive, read shall prompt for a continuation line
       when:

        * The shell reads an input line  ending  with  a  backslash,  unless  the  -r  option  is
          specified.

        * A here-document is not terminated after a <newline> is entered.

       The  line  shall  be  split  into fields as in the shell (see Field Splitting ); the first
       field shall be assigned to the first variable var, the second field to the second variable
       var,  and  so  on.   If  there are fewer var operands specified than there are fields, the
       leftover fields and their intervening separators shall be assigned to  the  last  var.  If
       there are fewer fields than vars, the remaining vars shall be set to empty strings.

       The  setting  of  variables  specified  by the var operands shall affect the current shell
       execution environment; see Shell Execution Environment . If it is called in a subshell  or
       separate utility execution environment, such as one of the following:

              (read foo)
              nohup read ...
              find . -exec read ... \;

       it shall not affect the shell variables in the caller's environment.

OPTIONS

       The  read  utility  shall  conform to the Base Definitions volume of IEEE Std 1003.1-2001,
       Section 12.2, Utility Syntax Guidelines.

       The following option is supported:

       -r     Do not treat a backslash character in any special way. Consider each  backslash  to
              be part of the input line.

OPERANDS

       The following operand shall be supported:

       var    The name of an existing or nonexisting shell variable.

STDIN

       The standard input shall be a text file.

INPUT FILES

       None.

ENVIRONMENT VARIABLES

       The following environment variables shall affect the execution of read:

       IFS    Determine the internal field separators used to delimit fields; see Shell Variables
              .

       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 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 .

       PS2    Provide  the  prompt string that an interactive shell shall write to standard error
              when a line ending with a backslash is read and the -r option was not specified, or
              if a here-document is not terminated after a <newline> is entered.

ASYNCHRONOUS EVENTS

       Default.

STDOUT

       Not used.

STDERR

       The standard error shall be used for diagnostic messages and prompts for continued input.

OUTPUT FILES

       None.

EXTENDED DESCRIPTION

       None.

EXIT STATUS

       The following exit values shall be returned:

        0     Successful completion.

       >0     End-of-file was detected or an error occurred.

CONSEQUENCES OF ERRORS

       Default.

       The following sections are informative.

APPLICATION USAGE

       The -r option is included to enable read to subsume the purpose of the line utility, which
       is not included in IEEE Std 1003.1-2001.

       The results are undefined if an end-of-file is detected following a backslash at  the  end
       of a line when -r is not specified.

EXAMPLES

       The following command:

              while read -r xx yy
              do
                  printf "%s %s\n" "$yy" "$xx"
              done < input_file

       prints a file with the first field of each line moved to the end of the line.

RATIONALE

       The read utility historically has been a shell built-in. It was separated off into its own
       utility to take advantage of the richer description of functionality  introduced  by  this
       volume of IEEE Std 1003.1-2001.

       Since  read affects the current shell execution environment, it is generally provided as a
       shell regular built-in. If it is called  in  a  subshell  or  separate  utility  execution
       environment, such as one of the following:

              (read foo)
              nohup read ...
              find . -exec read ... \;

       it does not affect the shell variables in the environment of the caller.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Shell Command Language

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 .