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argument hysteresis?

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# 8  
Old 07-09-2008
And you are also running it in the current shell so there is no real surprise that 0 args gives a non zero result since you used set on the previous run.
# 9  
Old 07-10-2008
Haha no this is not a joke, but I really just make my first steps in shell scripting, and I think forums are very helpful. So I was just playing with 'for' loops, '$#', '$@' ... I just copied some stuff from websites on shell scripting and played with them.

Hell don't know what the "set -- $arg_i" means, just read that it "should be done like this" (to test if the argument is not null or something?)

But it works if I comment out that line, what does that line mean then? Thanks a lot!

ps: am I right that it keeps in mind the last argument? When I give an argument list, it only keeps the last one...
Last edited by MarkZWEERS; 07-10-2008 at 01:22 AM.. Reason: ps
# 10  
Old 07-10-2008
Referring to reborg's point, you should avoid running your script with the . or source prefix. Traditionally you would allow scripts to be run in their own subshell, unless it has a particular requirement to modify the environment of your current shell, which results in the behaviour you observed (i.e. variable values are retained).
# 11  
Old 07-10-2008
I've asked a question about the '.' prefix in this thread:

https://www.unix.com/shell-programmin...#post302213109

thanks a lot!
# 12  
Old 07-10-2008
Quote:
Referring to reborg's point, you should avoid running your script with the . or source prefix. Traditionally you would allow scripts to be run in their own subshell, unless it has a particular requirement to modify the environment of your current shell, which results in the behaviour you observed (i.e. variable values are retained).
Just to clarify, the arguments are reset at every run regardless of the invocation - current shell vs. subshell:

Code:
$ cat arguments.sh
printf "You've typed %d arguments\n" $#
printf "The arguments are: %s\n" "$@"
$ . arguments.sh
You've typed 0 arguments
The arguments are:
$ . arguments.sh a
You've typed 1 arguments
The arguments are: a
$ . arguments.sh
You've typed 0 arguments
The arguments are:

And of course, when you invoke a script with the . (period) scriptname syntax you're modifying the current environment:

Code:
$ cat arguments.sh
printf "You've typed %d arguments\n" $#
printf "The arguments are: %s\n" "$@"
set -- "$@"
$ . arguments.sh
You've typed 0 arguments
The arguments are:
$ . arguments.sh a
You've typed 1 arguments
The arguments are: a
$ . arguments.sh
You've typed 1 arguments
The arguments are: a
$ ./arguments.sh
You've typed 0 arguments
The arguments are:
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