gets(n) Tcl Built-In Commands gets(n)
NAME
gets - Read a line from a channel
SYNOPSIS
gets channelId ?varName?
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 com-
mand. 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 charac-
ters 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 chan-
nelId 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 var-
Name 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(n), eof(n), fblocked(n), Tcl_StandardChannels(3)
KEYWORDS
blocking, channel, end of file, end of line, line, non-blocking, read
Tcl 7.5 gets(n)
tcl 8.6.0 - Generated Wed Jan 9 15:00:12 CST 2013