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fconfigure(n)	      Tcl Built-In Commands	    fconfigure(n)

_________________________________________________________________

NAME
       fconfigure - Set and get options on a channel

SYNOPSIS
       fconfigure channelId
       fconfigure channelId name
       fconfigure channelId name value ?name value ...?
_________________________________________________________________

DESCRIPTION
       The  fconfigure	command	 sets  and  retrieves options for
       channels.  ChannelId identifies the channel for	which  to
       set or query an option.	If no name or value arguments are
       supplied, the command returns a list containing	alternat-
       ing  option  names and values for the channel.  If name is
       supplied but no value then the command returns the current
       value  of  the given option.  If one or more pairs of name
       and value are supplied, the command sets each of the named
       options	to  the	 corresponding	value;	in  this case the
       return value is an empty string.

       The options described below are supported  for  all  chan-
       nels.  In addition, each channel type may add options that
       only it supports. See the manual	 entry	for  the  command
       that  creates  each  type of channels for the options that
       that specific type of channel supports. For  example,  see
       the manual entry for the socket command for its additional
       options.

       -blocking boolean
	      The -blocking option determines whether I/O  opera-
	      tions on the channel can cause the process to block
	      indefinitely.  The value of the option  must  be	a
	      proper  boolean  value.	Channels  are normally in
	      blocking mode;  if a channel is  placed  into  non-
	      blocking	mode  it will affect the operation of the
	      gets, read, puts, flush, and  close  commands;  see
	      the  documentation  for those commands for details.
	      For nonblocking mode to work correctly, the  appli-
	      cation  must  be	using the Tcl event loop (e.g. by
	      calling Tcl_DoOneEvent or invoking the  vwait  com-
	      mand).

       -buffering newValue
	      If newValue is full then the I/O system will buffer
	      output until its internal buffer is full	or  until
	      the  flush command is invoked. If newValue is line,
	      then the I/O system will automatically flush output
	      for  the	channel	 whenever  a newline character is
	      output. If newValue is none, the	I/O  system  will
	      flush  automatically  after every output operation.

Tcl			       7.5				1

fconfigure(n)	      Tcl Built-In Commands	    fconfigure(n)

	      The default is for -buffering to	be  set	 to  full
	      except  for  channels that connect to terminal-like
	      devices; for these channels the initial setting  is
	      line.

       -buffersize newSize
	      Newvalue	must  be an integer; its value is used to
	      set the size of  buffers,	 in  bytes,  subsequently
	      allocated	 for  this channel to store input or out-
	      put. Newvalue must be between ten and one	 million,
	      allowing	buffers	 of  ten  to one million bytes in
	      size.

       -eofchar char

       -eofchar {inChar outChar}
	      This option supports DOS file systems that use Con-
	      trol-z (\x1a) as an end of file marker.  If char is
	      not an empty string, then	 this  character  signals
	      end  of  file  when it is encountered during input.
	      For output, the end of  file  character  is  output
	      when  the	 channel is closed.  If char is the empty
	      string, then there is no special end of file  char-
	      acter  marker.  For read-write channels, a two-ele-
	      ment list specifies the  end  of	file  marker  for
	      input  and output, respectively.	As a convenience,
	      when setting the end-of-file character for a  read-
	      write  channel  you can specify a single value that
	      will apply  to  both  reading  and  writing.   When
	      querying	the end-of-file character of a read-write
	      channel,	a  two-element	list   will   always   be
	      returned.	  The  default	value for -eofchar is the
	      empty string in all cases except	for  files  under
	      Windows.	 In  that  case the -eofchar is Control-z
	      (\x1a) for reading and the empty string  for  writ-
	      ing.

       -translation mode

       -translation {inMode outMode}
	      In  Tcl  scripts the end of a line is always repre-
	      sented using a single newline character (\n).  How-
	      ever, in actual files and devices the end of a line
	      may be represented differently on	 different  plat-
	      forms,  or  even	for different devices on the same
	      platform.	 For example,  under  UNIX  newlines  are
	      used  in	files,	whereas	 carriage-return-linefeed
	      sequences are normally used in network connections.
	      On  input	 (i.e.,	 with  gets and read) the Tcl I/O
	      system automatically translates the  external  end-
	      of-line  representation  into  newline  characters.
	      Upon output  (i.e.,  with	 puts),	 the  I/O  system
	      translates  newlines  to	the  external end-of-line
	      representation.	The  default  translation   mode,

Tcl			       7.5				2

fconfigure(n)	      Tcl Built-In Commands	    fconfigure(n)

	      auto,  handles  all the common cases automatically,
	      but the -translation option provides explicit  con-
	      trol over the end of line translations.

	      The  value associated with -translation is a single
	      item for read-only and  write-only  channels.   The
	      value  is	 a  two-element list for read-write chan-
	      nels; the read translation mode is the  first  ele-
	      ment of the list, and the write translation mode is
	      the second element.  As a convenience, when setting
	      the  translation	mode for a read-write channel you
	      can specify a single value that will apply to  both
	      reading and writing.  When querying the translation
	      mode of a read-write channel,  a	two-element  list
	      will  always be returned.	 The following values are
	      currently supported:

	      auto   As the input translation mode,  auto  treats
		     any  of  newline (lf), carriage return (cr),
		     or carriage return	 followed  by  a  newline
		     (crlf)  as	 the  end of line representation.
		     The end  of  line	representation	can  even
		     change  from line-to-line, and all cases are
		     translated to  a  newline.	  As  the  output
		     translation  mode,	 auto  chooses a platform
		     specific representation; for sockets on  all
		     platforms	Tcl  chooses  crlf,  for all Unix
		     flavors, it chooses lf,  for  the	Macintosh
		     platform  it  chooses cr and for the various
		     flavors of Windows	 it  chooses  crlf.   The
		     default setting for -translation is auto for
		     both input and output.

	      binary No end-of-line translations  are  performed.
		     This  is nearly identical to lf mode, except
		     that in addition binary mode also	sets  the
		     end  of  file character to the empty string,
		     which disables it.	 See the  description  of
		     -eofchar for more information.

	      cr     The  end of a line in the underlying file or
		     device is represented by a	 single	 carriage
		     return  character.	 As the input translation
		     mode, cr mode converts carriage  returns  to
		     newline  characters.  As the output transla-
		     tion mode, cr mode translates newline  char-
		     acters  to	 carriage  returns.  This mode is
		     typically used on Macintosh platforms.

	      crlf   The end of a line in the underlying file  or
		     device  is	 represented by a carriage return
		     character followed by a linefeed  character.
		     As	 the  input  translation  mode, crlf mode
		     converts carriage-return-linefeed	sequences

Tcl			       7.5				3

fconfigure(n)	      Tcl Built-In Commands	    fconfigure(n)

		     to newline characters.  As the output trans-
		     lation mode, crlf	mode  translates  newline
		     characters	   to	 carriage-return-linefeed
		     sequences.	 This mode is typically	 used  on
		     Windows  platforms	 and  for network connec-
		     tions.

	      lf     The end of a line in the underlying file  or
		     device  is	 represented  by a single newline
		     (linefeed)	 character.   In  this	mode   no
		     translations  occur  during  either input or
		     output.  This mode is typically used on UNIX
		     platforms.

SEE ALSO
       close(n), flush(n), gets(n), puts(n), read(n), socket(n)

KEYWORDS
       blocking,  buffering, carriage return, end of line, flush-
       ing, linemode, newline, nonblocking, platform, translation

Tcl			       7.5				4

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