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Full Discussion: Eval set -- and more
Top Forums UNIX for Beginners Questions & Answers Eval set -- and more Post 302990823 by Corona688 on Wednesday 1st of February 2017 10:26:12 AM
Old 02-01-2017
-- "$@" just means, "take the following arguments literally" and "all the following arguments, properly separated and quoted". If your arguments are "a b" "c d" "e f", "$@" will put them in as "a b" "c d" "e f", not "a" "b" "c" "d" "e" "f".

The 'shift' eats a commandline argument, i.e. converts $1=a, $2=b, $3=c, $4=d into $1=b, $2=c, $3=d. shift 2 moves it all the way to $1=c, $2=d. It's done since that particular branch uses an argument, so it has to remove two things from the list (the -r and the argument following it) not just one.

I have no idea why they're doing 'eval set', only theories. That's dangerous and dumb. They may be trying to process quotes inside quotes.



They are getting the values from 'getopt', the standard way to handle commandline arguments. I can't really explain its workings, but I'm sure others can.

Last edited by Corona688; 02-01-2017 at 11:48 AM..
 

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eval(1T)						       Tcl Built-In Commands							  eval(1T)

__________________________________________________________________________________________________________________________________________________

NAME
eval - Evaluate a Tcl script SYNOPSIS
eval arg ?arg ...? _________________________________________________________________ DESCRIPTION
Eval takes one or more arguments, which together comprise a Tcl script containing one or more commands. Eval concatenates all its argu- ments in the same fashion as the concat command, passes the concatenated string to the Tcl interpreter recursively, and returns the result of that evaluation (or any error generated by it). Note that the list command quotes sequences of words in such a way that they are not further expanded by the eval command. EXAMPLE
This procedure acts in a way that is analogous to the lappend command, except it inserts the argument values at the start of the list in the variable: proc lprepend {varName args} { upvar 1 $varName var # Ensure that the variable exists and contains a list lappend var # Now we insert all the arguments in one go set var [eval [list linsert $var 0] $args] } KEYWORDS
concatenate, evaluate, script SEE ALSO
catch(1T), concat(1T), error(1T), list(1T), subst(1T), tclvars(1T) ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +--------------------+-----------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +--------------------+-----------------+ |Availability | SUNWTcl | +--------------------+-----------------+ |Interface Stability | Uncommitted | +--------------------+-----------------+ NOTES
Source for Tcl is available on http://opensolaris.org. Tcl eval(1T)
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