Bioperl Training Exercise 2

#!/usr/bin/perl
$variable = 42;
print $variab1e;

• Create a script containing the lines above and make it executable. Run it and see what happens. What needs to be done to fix it ?

my_script.pl
#!/usr/bin/perl   $variable1 = 42; # typo: $variab1e should be $variable # autovivification !!! print $variable;

• What needs to be done to prevent these kind of mistakes ?

my_script.pl

Always use the strict pragma ! Look at the error message and get used to it. Happens a lot of times, but fortunately easy to fix. #!/usr/bin/perl use strict;   my $variable = 42; print $variab1e; BTW: there is a nice tool which explains error messages for you. Simply run splain and paste in Perl's one line error message. Alternatively you can do it like this (my_script.pl is the script that does not run because of an error, e.g. the little script above): $ my_script.pl 2>&1 | splain