in reply to Re: Perl Project: Text Search
in thread Perl Project: Text Search

I think I got it all figured out now, I just am having trouble with the error trapping. My error trap for a nonexistent username doesnt work. 
#!/usr/bin/perl

$filename = '/etc/passwd.bak';

open(FILE, $filename) or die "Could not read from $filename, program h
+alting.";
while(<FILE>)
{
   chomp;

   @fields = split(':', $_);

   if ($ARGV[0] eq $fields[0]){
       print "Home directory: $fields[5]\n";
       print "Shell used: $fields[6]\n";
       exit 0;


} elsif ($ARGV[0] != $fields[0]){
        print "User: username does not exist.\n";
        exit 0;

} elsif ((@ARGV > 1) || (@ARGV == 0)){
        print "Please enter at least one but only one argument.\n";
        exit 0;
}

}
close FILE;

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Re^3: Perl Project: Text Search
by crashtest (Curate) on Apr 09, 2010 at 00:10 UTC

    Your two elsif blocks don't belong in the loop. If they're in the loop, they execute for every line of the file, which is not what you want.

    You only know for sure that a username wasn't in the file after you've worked through every single line of the file. In fact, since you immediately exit the program after finding and printing the information for a user, you know that if you make it through the entire while(<FILE>) loop, the username wasn't found. Print the error message at that point.

    Similarly, the check that exactly one argument was provided needs to be done before you enter the while loop, not within it. Why even open the passwd file if the program wasn't run correctly, right?

    Update: the indentation of your code is strange - you do realize that the if/elsif/elsif is within the while loop - hence is being executed once for every line in the input file? Nesting in Perl is controlled with curly braces ({ and }), not by indentation like in some other languages.

[reply]
[d/l]
[select]
      I've got it working about 99% correctly now. Thanks for your help! 
      #!/usr/bin/perl

$filename = '/etc/passwd.bak';

    if ($ARGV[0] != $fields[0]){
        print "User: username does not exist.\n";
        exit 0; }

    elsif ((@ARGV > 1) || (@ARGV == 0)){
        print "Please enter at least one but only one argument.\n";
        exit 0;  }


open(FILE, $filename) or die "Could not read from $filename, program h
+alting.";
while(<FILE>)

{
    chomp;

    @fields = split(':', $_);

    if ($ARGV[0] eq $fields[0]){
        print "Home directory: $fields[5]\n";
        print "Shell used: $fields[6]\n";
        exit 0;  }

}

close FILE;

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[reply]
[d/l]
      Yes I am aware my indentation is strange. I am not a very good programmer lol. I just do things in a way that seems logical in my head. Which often seems stupid for everyone else. Thanks for your tip on where to put the error trapping statements. I should be able to figure it out now.
[reply]
Re^3: Perl Project: Text Search
by Sharp (Initiate) on Apr 08, 2010 at 21:02 UTC
    That was me that posted the code just forgot to login.
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