perl: When dealing with files that do not exist

joeyg · #1 (**permalink**) 02-20-2008

I have a process run weekly where I must convert data formats for about thirty files. I read a text file that provides all of the filenames and switch settings.

My perl code is:

Code:

for ($j = 1; $j <= $k; $j++)
{

   open(FIN2,$fin2) || die "open: $!";

   do other stuff
}

Every once in a while, one of the files is empty, & this is ok.
But the perl program aborts at that open line. Right now, when this happens, I simply remove the file info from the text file listing, and restart. But, I must remember to put the line(s) back in for the next week.

QUESTION:
is it better to do a "next" when the file open fails, or
do some kind of File::stat command to know if the file exists first

In shell scripting, one can do an "if [ -e filename ] " kind of thing

KevinADC · #2 (**permalink**) 02-20-2008

It all depends on your requirements, but a 'next' will work fine:

Code:

for ($j = 1; $j <= $k; $j++)
{

   open(FIN2,$fin2) or do {warn "Can't open $fin2: $!"; next;};

   do other stuff
}

remove the do {warn} stuff if you don't need any error handling.

HPAVC · #3 (**permalink**) 02-20-2008

Quote:

Originally Posted by joeyg

In shell scripting, one can do an "if [ -e filename ] " kind of thing

you can if (-f "/etc/passwd") { warn "file exists" } in perl too, most of the modern test flags exist.

the big problem i have is when the file is after the mundane open(FH,..) that your doing. and the print FH "" fails. This take a little bit of care and feeding but its worth it imo.

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