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problem with exec statement

Posted by arunsri (arunsri), 19 April 2006
Hi

I am trying to execute a C program from a TCl script using the "exec" command. The program accepts a number of command line parameters.

I get these parameters thru' a network and store it in a string, say "args". Now, when I do

exec $prog $args,

all the arguments in the variable "args" are passed as a single string to the C program and thus causing it to fail.

So,how do we execute the C program with the "exec statement" (with each argument appearing as a seperate string )as we would normally on a command line?

thanks in advance
Arun

Posted by admin (Graham Ellis), 19 April 2006
Does this help? ...

Code:
# Code that fails if there's more than one command line parameter

# puts $argv
# set r [exec grep JBoss $argv]
# puts $r

# Code that works for multiple command line parameters

puts $argv
set r [open "| grep JBoss $argv"]
set result [read $r]
puts $result


(Tested, worked for me!)

Note - exec is very low level and needs you to split up and provide separately each of the command line parameters as that's what Unix and Linux do internally.  It's much better to let open or something like that do the work for you.

Posted by arunsri (arunsri), 22 April 2006
Hi graham, thanks for the tip. It works for me.Even this trick seems to work. (Please CMIIW)

set cmd "exec $prog $arg"
eval $cmd

rgds
Arun



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