gets

gets(3tcl)                    Tcl Built-In Commands                   gets(3tcl)



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NAME
       gets - Read a line from a channel

SYNOPSIS
       gets channelId ?varName?
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DESCRIPTION
       This command reads the next line from channelId, returns everything in
       the line up to (but not including) the end-of-line character(s), and
       discards the end-of-line character(s).

       ChannelId must be an identifier for an open channel such as the Tcl
       standard input channel (stdin), 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 input.

       If varName is omitted the line is returned as the result of the command.
       If varName is specified then the line is placed in the variable by that
       name and the return value is a count of the number of characters
       returned.

       If end of file occurs while scanning for an end of line, the command
       returns whatever input is available up to the end of file.  If channelId
       is in non-blocking mode and there is not a full line of input available,
       the command returns an empty string and does not consume any input.  If
       varName is specified and an empty string is returned in varName because
       of end-of-file or because of insufficient data in non-blocking mode, then
       the return count is -1.  Note that if varName is not specified then the
       end-of-file and no-full-line-available cases can produce the same results
       as if there were an input line consisting only of the end-of-line
       character(s).  The eof and fblocked commands can be used to distinguish
       these three cases.

EXAMPLE
       This example reads a file one line at a time and prints it out with the
       current line number attached to the start of each line.

              set chan [open "some.file.txt"]
              set lineNumber 0
              while {[gets $chan line] >= 0} {
                  puts "[incr lineNumber]: $line"
              }
              close $chan


SEE ALSO
       file(3tcl), eof(3tcl), fblocked(3tcl), Tcl_StandardChannels(3tcl)


KEYWORDS
       blocking, channel, end of file, end of line, line, non-blocking, read



Tcl                                    7.5                            gets(3tcl)