Open Perl file problem

Question

Open Perl file problem

I am having trouble trying to print from a file. Any ideas? Thanks to

open(STDOUT,">/home/int420_101a05/shttpd/htdocs/receipt.html"); 
#Results of a sub-routine
&printReceipt; 
close(STDOUT);

open(INF,"/home/int420_101a05/shttpd/htdocs/receipt.html"); $emailBody = <INF>; 
close(INF); 
print $emailBody;

ERRORS: Filehandle STDOUT reopened as INF only for input at ./test.c line 6. 
print() on closed filehandle STDOUT at ./test.c line 9.

+2

perl cgi

AlexBrand Apr 12 10 at 15:10

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3 answers

If you want to temporarily change standard output, use the select builtin. Another option is to localize the typeglob first:

{
    local *STDOUT;
    open STDOUT, '>', 'outfile.txt' or die $!;
    print "Sent to file\n";
}

+1

Eugene yarmash Apr 12 10 at 15:15

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Do not try to open the STDOUT handle. If you want to print to STDOUT, just use print

(no file descriptor argument). If you want to print something other than STDOUT, use a different name.

0

JSB ձոգչ Apr 12 10 at 15:14

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DVK · Accepted Answer · 2010-04-12T15:14:47+0000

This discussion addresses the technical reason for the message . The relevant information from the stream is as follows:

From the open (2) manpage:

When the call is successful, the file descriptor returned will be the lowest file descriptor not currently open to the process.

But STDOUT still applies to filehandle # 1. This warning might be helpful. While it could be argued that further use of STDOUT as an output filehandle raises a warning as well ...

So, to summarize, you closed STDOUT (file descriptor 1) and your file will open as FD # 1. This is because of properties open()'s

.
As others have pointed out, the real reason you're having this problem is because you shouldn't use STDOUT to print to a file unless there is a special case where it needs to be.

Instead, open the file for writing with a new file descriptor:
```
open (OUTFILE, "> / home / int420_101a05 / shttpd / htdocs / receipt.html")
   || die "Could not open: $!";
print OUTFILE "data";
close (OUTFILE);
```
To print to a file descriptor from a subroutine, simply pass the file descriptor as a parameter .

The best way to do it is to create an object IO::File

and pass that object around
```
my $ filehandle = IO :: File-> new ("> $ filename") || die "error: $!";
mySub ($ filehandle);

sub mySub {
 my $ fh = shift;
 print $ fh "stuff" || die "could not print $!";    
}
```
You can also set a specific file descriptor as the default file descriptor for printing by default using select

but this LOT is more fragile and should be reserved in favor of the IO :: File solution.

Open Perl file problem

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