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Full Discussion: Help understanding the script
Top Forums Shell Programming and Scripting Help understanding the script Post 302983562 by RudiC on Thursday 13th of October 2016 04:44:51 AM
Old 10-13-2016
That's a strange script, and it is difficult to read/understand. Try e.g. serious indentation, and the proposals given above. For your special question, see here:
Code:
PrevHostname=''                 # preset variable to empty
PrevBackup=0                    # preset variable to 0
while read input                # read variable "input" from stdin
                                # input contents:   "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                                # input char count:  01234567890123456789012345 
                                # result in variables:
do Month=${input:0:3}           # ABC
   Day=${input:4:2}             # DE
   Hostname=${input:13:12}      # NOPQRSTUVWX

This User Gave Thanks to RudiC For This Post:
Chubler_XL
 

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LEARN ABOUT X11R4

gets

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 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  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 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(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)
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