CODEWITHSUNDEEP
perlfile
mac
mac

Reputation: 930

Reading data from file and creating a file and writing data is the file is not found

I have come into a situation where I need to read 2 lines data (username and password) from a file called login.txt(in current dir). After reading the username (1st line) has to be stored in $user and the second line (password) has to be stored in $pass.

In case if this file is not found, I have to prompt the user to enter the username and password and store it in $user and $pass and create the file login.txt(in currect dir) and write these two lines into the file. 

my $user;
my $pass;

my $login = "login.txt";


unless (-e $login) {
print "Entering first time execution mode....!\n";
sleep(2);

print "Enter username:\n";
$user = <STDIN>;
chomp($user);
print "Enter password:\n";
$pass = <STDIN>;
chomp($pass);
unless(open LINFO, '>'.$login) {
# Die with error message 
# if we can't open it.
die "\nUnable to create $login\n";
}

print LINFO "$user\n";
print LINFO "$pass\n";

close LINFO;
} 


if (-e $login) {

open (LINFO, '$login') or die "Cant open\n";

while( my $line = <LINFO>)  {   
print $line; 
chomp($line); 

if    ($. == 1) { $user = $line; }

elsif ($. == 2) { $pass = $line; }

last if $. == 2;

}

close LINFO;

}

print $pass;
print $user;

When the file is doesn't exists everything works fine (even $user and $pass gets printed), but will get a error message as below :- 

readline() on closed filehandle LINFO at loginfile.pl line 43.

If the file already exists then I get following error 

readline() on closed filehandle LINFO at loginfile.pl line 43.
Use of uninitialized value $pass in print at loginfile.pl line 59.
Use of uninitialized value $user in print at loginfile.pl line 60.

Not sure whats the issue here

Upvotes: 0

Views: 75

Answers (2)

TLP
TLP

Reputation: 67900

Why is it exiting if it doesn't find the login.txt file? Because of the die statement? Here's perldoc -f die:

die LIST

die raises an exception. Inside an eval the error message is stuffed into $@ and the eval is terminated with the undefined value. If the exception is outside of all enclosing evals, then the uncaught exception prints LIST to STDERR and exits with a non-zero value. If you need to exit the process with a specific exit code, see exit.

While this is not terribly clear (to be precise, its horribly unclear for a newbie), you should probably know that die means that the program exits, execution stops there.

When using open, this is the recommended practice, since often any error in open calls should be considered fatal. You however ignore this open call and use another open on the same file handle later on in that block. The only reason I can see for 

unless(open LINFO, $login) {

Would then be that you are trying to determine if the file exists, and you can read it. For this purpose, you can use the -X commands, e.g.

if (-e $login)     # if file exists
if (-r $login)     # effective uid/gid can read file
...

Upvotes: 1

tauli
tauli

Reputation: 1420

You have to enclose the conditions for if and elsif in parentheses. Also be careful where to use = and ==. This should work for you:

if    ($. == 1) { $user = $line;  }
elsif ($. == 2) { $pass = $line;  }

Upvotes: 1

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