View Full Version : [SOLVED] Perl: Open file or die AND set variable

November 11th, 2008, 02:13 PM
Hey guys and gals, I'm posting this as a regular user, I need some help! I don't know a lot about perl, so here goes:

I am opening a file as follows:

open(CONFIG , $filename) ||
die "$filename is not available.\n";
I would like to also be able to set my return value variable ($RETVAL) to 1 in the case that die is executed, but I don't know how to combine the two commands.

Perhaps I need to run the open function with an eval expression (which I know nothing about)? Or can I just do something like

if (!CONFIG) {
Thanks in advance!

November 11th, 2008, 02:19 PM
maybe put $RETVAL=1; before die?

November 11th, 2008, 02:25 PM
maybe put $RETVAL=1; before die?

You mean like this?

open(CONFIG , $filename) ||
$RETVAL=1; die "$filename is not available.\n";

I get

Can't modify logical or (||) in scalar assignment at (./scriptname) line 148, near "1;"
Execution of (./scriptname) aborted due to compilation errors.

If there isn't a way to combine two commands after the or (||) statement, what is the best way to capture the fact that the file open failed before the next part of the code executes? If I can do that, I can set the return value and break out of the subroutine. That's why I asked about eval as well, I just don't know how to use it effectively.

November 11th, 2008, 02:47 PM
sub die_me {
$retval = 1;
die "$filename is not available.\n"

open(CONFIG , $filename) || die_me();

November 11th, 2008, 02:51 PM
I think there is no need to set $RETVAL manually, there are lots of environment variables that perl handles automatically, check out This page (http://www.sarand.com/td/ref_perl_reserve.html).

I think you are looking for the $! variable, but I'm not sure, you can check the list to see which one you should look for.

EDIT: This list (http://www.kichwa.com/quik_ref/spec_variables.html)is shorter and friendlier

November 11th, 2008, 03:22 PM
OK, it would appear that using die() is not allowing me to set return codes in my program since I guess it sets its own the returns up the function stack until it exits. I was able to achieve my goal with:

open(CONFIG , $filename) || do {
print "$filename is not available.\n";
Using the two lines above in a separate function also worked (which is what gave me the idea to use a do {} statement. A separate function didn't help either with trying to combine my own return values with die().

I will attempt to capture die() further up in the stack so that I can still use proper error handling. Thank you for the help!