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RedHat 9 (Linux i386) - man page for fconfigure (redhat section n)

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


       fconfigure - Set and get options on a channel

       fconfigure channelId
       fconfigure channelId name
       fconfigure channelId name value ?name value ...?

       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 alternating 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

       The options described below are supported for all channels. 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 operations 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  non-
	      blocking	mode  to work correctly, the application must be using the Tcl event loop
	      (e.g. by calling Tcl_DoOneEvent or invoking the vwait command).

       -buffering newValue
	      If newValue is full then the I/O system will buffer output until its internal  buf-
	      fer  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 char-
	      acter is output. If newValue is none, the I/O system will flush automatically after
	      every output operation.  The default is for -buffering to be set to full except for
	      channels that connect to terminal-like devices; for these channels the initial set-
	      ting is line.  Additionally, stdin and stdout are intially set to line, and  stderr
	      is set to none.

       -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	output.  Newvalue
	      must  be	between ten and one million, allowing buffers of ten to one million bytes
	      in size.

       -encoding name										  |
	      This option is used to specify the encoding of the channel, so that the data can be |
	      converted  to  and  from Unicode for use in Tcl.	For instance, in order for Tcl to |
	      read characters from a Japanese file in shiftjis and properly process  and  display |
	      the contents, the encoding would be set to shiftjis.  Thereafter, when reading from |
	      the channel, the bytes in the Japanese file would be converted to Unicode  as  they |
	      are  read.   Writing  is also supported - as Tcl strings are written to the channel |
	      they will automatically be converted to the specified encoding on output. 	  |

	      If a file contains pure binary data (for instance, a JPEG image), the encoding  for |
	      the channel should be configured to be binary.  Tcl will then assign no interpreta- |
	      tion to the data in the file and simply read or write raw bytes.	 The  Tcl  binary |
	      command can be used to manipulate this byte-oriented data.			  |

	      The  default  encoding  for newly opened channels is the same platform- and locale- |
	      dependent system encoding used for interfacing with the operating system. 	  |

       -eofchar char

       -eofchar {inChar outChar}
	      This option supports DOS file systems that use Control-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 out-
	      put when the channel is closed.  If char is the empty string, then there is no spe-
	      cial end of file character marker.  For read-write  channels,  a	two-element  list
	      specifies  the  end of file marker for input and output, respectively.  As a conve-
	      nience, 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 writing.

       -translation mode

       -translation {inMode outMode}
	      In Tcl scripts the end of a line is always represented using a single newline char-
	      acter (\n).  However, in actual files and devices the end of a line may  be  repre-
	      sented  differently  on  different  platforms, or even for different devices on the
	      same platform.  For example, under UNIX newlines are used in  files,  whereas  car-
	      riage-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, auto, handles all the common cases automatically, but the
	      -translation option provides explicit control 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 channels; the read
	      translation mode is the first element 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  sup-

	      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 sock-
		     ets 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 Win-
		     dows 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  charac- |
		     ter  to the empty string (which disables it) and sets the encoding to binary |
		     (which disables encoding filtering).  See the description	of  -eofchar  and |
		     -encoding for more information.

	      cr     The  end of a line in the underlying file or device is represented by a sin-
		     gle carriage return character.  As the input translation mode, cr mode  con-
		     verts  carriage  returns  to  newline characters.	As the output translation
		     mode, cr mode translates newline characters 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 car-
		     riage return character followed by  a  linefeed  character.   As  the  input
		     translation  mode,  crlf mode converts carriage-return-linefeed sequences to
		     newline characters.  As the output translation mode,  crlf  mode  translates
		     newline characters to carriage-return-linefeed sequences.	This mode is typ-
		     ically used on Windows platforms and for network connections.

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

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

       blocking, buffering, carriage return, end of line, flushing, linemode, newline,	nonblock-
       ing, platform, translation, encoding, filter, byte array, binary

Tcl					       8.1				    fconfigure(n)

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