NAME

       puts - Write to a channel

SYNOPSIS

       puts ?-nonewline? ?channelId? string
_________________________________________________________________

DESCRIPTION

       Writes the characters given by string to the channel given by channelId.

       ChannelId  must  be  an identifier for an open channel such as a Tcl standard channel (stdout or stderr), │
       the return value from an invocation of open or socket, or  the  result  of  a  channel  creation  command │
       provided by a Tcl extension. The channel must have been opened for output.

       If  no channelId is specified then it defaults to stdout. Puts normally outputs a newline character after
       string, but this feature may be suppressed by specifying the -nonewline switch.

       Newline characters in the output are  translated  by  puts  to  platform-specific  end-of-line  sequences
       according  to  the current value of the -translation option for the channel (for example, on PCs newlines
       are normally replaced with carriage-return-linefeed sequences).  See the fconfigure manual  entry  for  a
       discussion on ways in which fconfigure will alter output.

       Tcl  buffers  output internally, so characters written with puts may not appear immediately on the output
       file or device;  Tcl will normally delay output until the buffer is full or the channel is  closed.   You
       can force output to appear immediately with the flush command.

       When  the  output  buffer  fills up, the puts command will normally block until all the buffered data has
       been accepted for output by the operating system.  If channelId is in  nonblocking  mode  then  the  puts
       command  will  not  block even if the operating system cannot accept the data.  Instead, Tcl continues to
       buffer the data and writes it in the background as fast as the underlying file or device can  accept  it.
       The  application  must  use the Tcl event loop for nonblocking output to work;  otherwise Tcl never finds
       out that the file or device is ready for more output data.  It  is  possible  for  an  arbitrarily  large
       amount  of  data  to be buffered for a channel in nonblocking mode, which could consume a large amount of
       memory.  To avoid wasting memory, nonblocking I/O should normally be used in an event-driven fashion with
       the fileevent command (don't invoke puts unless you have recently been notified via a file event that the
       channel is ready for more output data).

EXAMPLES

       Write a short message to the console (or wherever stdout is directed):
              puts "Hello, World!"

       Print a message in several parts:
              puts -nonewline "Hello, "
              puts "World!"

       Print a message to the standard error channel:
              puts stderr "Hello, World!"

       Append a log message to a file:
              set chan [open my.log a]
              set timestamp [clock format [clock seconds]]
              puts $chan "$timestamp - Hello, World!"
              close $chan

SEE ALSO

       file(3tcl), fileevent(3tcl), Tcl_StandardChannels(3tcl)

KEYWORDS

       channel, newline, output, write