Hi,

I am looking to insert a couple of lines in the output. The problem is that when I try "puts $fh..." the lines are inserted only at the end of the output file and not immediately, where the last line was read...

I've attached a sample script to make more sense of my problem..... The output file which needs modification is attched after the script...

======
#------------
Sample script
#------------

set fh [open "...123.txt" r+]
while {[gets $fh line] > 0} {
        set temp $line
        if {[string eq [lindex $temp 0] "12345"]==1} {
                puts $fh "one two three four five"
                } elseif {[string eq [lindex $temp 0] "67890"]==1} {
                        puts $fh "six seven eight nine zero"
                } else { 
                }        
        }

#--#--#--#--#--
======
Existing output file

======
12345

45678

Insert the names of the above digits...

...immediately after the number

67890

90123

...& not at the end

This is the End of line. Do not print below this!!
======

[AM] (25 september 2011) This is only possible by making a copy of the file and renaming it:

======
set fh [open "...123.txt" r]
set fhout [open "...123.txt-new" w]
while {[gets $fh line] > 0} {
        puts $fhout $line
        set temp $line
        if {[string eq [lindex $temp 0] "12345"]==1} {
                puts $fhout "one two three four five"
                } elseif {[string eq [lindex $temp 0] "67890"]==1} {
                        puts $fhout "six seven eight nine zero"
                } else { 
                }        
        }
close $fh
close $fhout
file rename "...123.txt-new" "...123.txt"
======

This is not a limitation of Tcl - this is an operation that the operating system does not support
directly. It simply cannot shift the data "downwards" - just think of a file of several millions
of lines and you want to insert a new line after each original line ...