Index for Section 1

Alphabetical listing for R

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read(1)
NAME
  read - Reads a line from standard input

SYNOPSIS
  read [-r] var...

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  read:	 XCU5.0

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

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

				       Note

	 The -r option is included to enable read to subsume the purpose of
	 the obsolete line utility.

OPERANDS
  var The name of an existing or non-existing shell variable.

DESCRIPTION
  The read utility reads a single line from standard input.

  By default, unless the -r option is specified, backslash (\) acts as an
  escape character.  If standard input is a terminal device and the invoking
  shell is interactive, read prompts for a continuation line in the following
  cases:

    ·  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 character is
       entered.

  The line is split into fields as in the shell (see the sh(1) reference
  page); the first field is assigned to the first variable var, the second
  field to the second variable var, and so forth.  If there are fewer var
  parameters specified than there are fields, the leftover fields and their
  intervening separators are assigned to the last var.	If there are fewer
  fields than vars, the remaining vars are set to empty strings.

  The setting of variables specified by the var parameters affects the
  current shell execution environment.	If read is called in a subshell or
  separate utility execution environment, such as one of the following, it
  does not affect the shell variables in the caller's environment:

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

NOTES
  The -r option is included to enable read to subsume the purpose of the
  obsolete line utility.

RESTRICTIONS
  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.

EXIT STATUS
  The following exit values are returned:

  0   Successful completion.

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

EXAMPLES
  The following command prints a file with the first field of each line moved
  to the end of the line:

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

ENVIRONMENT VARIABLES
  The following environment variables affect the execution of read:

  IFS Determines the internal field separators used to delimit fields.

  LANG
      Provides a default value for the internationalization variables that
      are unset or null.  If LANG is unset or null, the corresponding value
      from the default locale is used.	If any of the internationalization
      variables contain an invalid setting, the utility behaves as if none of
      the variables had been defined.

  LC_ALL
      If set to a non-empty string value, overrides the values of all the
      other internationalization variables.

  LC_CTYPE
      Determines the locale for the interpretation of sequences of bytes of
      text data as characters (for example, single-byte as opposed to
      multibyte characters in arguments).

  LC_MESSAGES
      Determines the locale used to affect the format and contents of
      diagnostic messages written to standard error.

  NLSPATH
      Determines the location of message catalogues for the processing of
      LC_MESSAGES.

  PS2 Provides the prompt string that an interactive shell will 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 character is entered.

SEE ALSO
  Commands:  line(1)

  Functions:  fread(3)

  Standards:  standards(5)

Index for Section 1

Alphabetical listing for R

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