Manual Pages for UNIX Operating System command usage for man read

User Commands                                             read(1)



NAME
     read - read a line from standard input

SYNOPSIS
  /usr/bin/read
     /usr/bin/read [-r] var...


  sh
     read name...


  csh
     set variable= $<


  ksh
     read [-prsu [n]] [name ? prompt] [name]...


  ksh93
     read [-ACprs] [-d delim] [-n nsize] [-N nsize] [-t timeout]
          [-u unit] [vname?prompt] [vname... ]


DESCRIPTION
  /usr/bin/read
     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 when:

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

         o    A here-document is not terminated after  a  NEWLINE
              character is entered.


     The line is split into fields as in  the  shell.  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  operands  specified  than  there are fields, the
     leftover fields and their intervening separators is assigned
     to  the  last  var. If there are fewer fields than vars, the
     remaining vars is set to empty strings.






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User Commands                                             read(1)



     The setting of  variables  specified  by  the  var  operands
     affects  the  current  shell execution environment. If it is
     called in a sub-shell or separate utility execution environ-
     ment, such as one of the following:

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




     It does not affect  the  shell  variables  in  the  caller's
     environment.


     The standard input must be a text file.

  sh
     One line is read from the  standard  input  and,  using  the
     internal  field  separator,  IFS (normally space or tab), to
     delimit word boundaries, the first word is assigned  to  the
     first  name,  the second word to the second name, and so on,
     with leftover words assigned to the last name. Lines can  be
     continued  using \newline. Characters other than NEWLINE can
     be  quoted  by  preceding  them  with  a  backslash.   These
     backslashes  are removed before words are assigned to names,
     and no interpretation is done on the character that  follows
     the  backslash.  The return code is 0, unless an end-of-file
     is encountered.

  csh
     The notation:

       set variable = $<




     loads one line of standard input as the value for  variable.
     (See csh(1)).

  ksh
     The shell input mechanism. One line is read and is broken up
     into  fields  using the characters in IFS as separators. The
     escape character, (\), is used to remove any special meaning
     for  the  next  character  and for line continuation. In raw
     mode, the -r, the , and the \ character are not treated spe-
     cially.  The  first field is assigned to the first name, the
     second field to the second name, and so  on,  with  leftover
     fields  assigned  to the last name. The -p option causes the
     input line to be taken from the  input  pipe  of  a  process



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User Commands                                             read(1)



     spawned  by  the  shell using |&. If the -s flag is present,
     the input is saved as a command in  the  history  file.  The
     flag  -u  can be used to specify a one digit file descriptor
     unit n to read from. The file descriptor can be opened  with
     the  exec  special  command. The default value of n is 0. If
     name is omitted, REPLY is used as the default name. The exit
     status is 0 unless the input file is not open for reading or
     an end-of-file is encountered. An end-of-file  with  the  -p
     option  causes  cleanup for this process so that another can
     be  spawned.  If  the  first  argument  contains  a  ?,  the
     remainder of this word is used as a prompt on standard error
     when the shell is interactive. The exit status is  0  unless
     an end-of-file is encountered.

  ksh93
     read reads a line from standard input  and  breaks  it  into
     fields using the characters in the value of the IFS variable
     as separators. The escape character, \, is  used  to  remove
     any special meaning for the next character and for line con-
     tinuation unless the -r option is specified.


     If there are more variables than fields, the remaining vari-
     ables are set to empty strings. If there are fewer variables
     than fields,  the  leftover  fields  and  their  intervening
     separators  are  assigned to the last variable. If no var is
     specified, the variable REPLY is used.


     When var has the binary attribute and -n or -N is specified,
     the bytes that are read are stored directly into var.


     If you specify ?prompt after the first var, read displays  a
     prompt  on  standard error when standard input is a terminal
     or pipe.

OPTIONS
  /usr/bin/read, ksh
     The following option is supported by /usr/bin/read and ksh:

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


  ksh93
     The following options are supported by ksh93:

     -A            Unset var, and create an  indexed  array  con-
                   taining  each  field  in  the line starting at
                   index 0.




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User Commands                                             read(1)



     -C            Unset var and read var as a compound variable.


     -d delim      Read until delimiter delim instead of  to  the
                   end of line.


     -n nsize      Read at most nsize bytes. Binary field size is
                   in bytes.


     -N nsize      Read exactly nsize bytes. Binary field size is
                   in bytes.


     -p            Read from the current  co-process  instead  of
                   standard  input. An end of file causes read to
                   disconnect the co-process so that another  can
                   be created.


     -r            Do not treat \ specially when  processing  the
                   input line.


     -s            Save a copy of the input as an  entry  in  the
                   shell history file.


     -t timeout    Specify a timeout in seconds when reading from
                   a terminal or pipe.


     -u fd         Read from file descriptor number fd instead of
                   standard input. The default value is 0.


     -v            When reading  from  a  terminal,  display  the
                   value  of  the  first variable and use it as a
                   default value.


OPERANDS
     The following operand is supported:

     var    The name of an existing or non-existing  shell  vari-
            able.


EXAMPLES
     Example 1 Using the read Command




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User Commands                                             read(1)



     The following example for /usr/bin/read prints a  file  with
     the first field of each line moved to the end of the line:


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



ENVIRONMENT VARIABLES
     See environ(5) for descriptions of the following environment
     variables  that  affect the execution of read: LANG, LC_ALL,
     LC_CTYPE, LC_MESSAGES, and NLSPATH.

     IFS    Determines the internal field separators used to del-
            imit fields.


     PS2    Provides the prompt string that an interactive  shell
            writes  to  standard  error when a line ending with a
            backslash is read and the -r option  was  not  speci-
            fied, or if a here-document is not terminated after a
            NEWLINE character is entered.


EXIT STATUS
     The following exit values are returned:

     0     Successful completion.


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


ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:

  /usr/bin/read, csh, ksh, sh














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User Commands                                             read(1)



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWcs                      |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | Standard                    | See standards(5).           |
    |_____________________________|_____________________________|


  ksh93
     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWcsu                     |
    |_____________________________|_____________________________|
    | Interface Stability         | Uncommitted                 |
    |_____________________________|_____________________________|


SEE ALSO
     csh(1), ksh(1), ksh93(1),  line(1),  set(1),  sh(1),  attri-
     butes(5), environ(5), standards(5)































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