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gets (n)

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 nonblocking 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, nonblocking, read Tcl 7.5 gets(n)