Convert tab data into HTML tables with a Perl one-liner

Quick one-liner for generating a HTML table from tab delimited input. Either pipe in your data or include the file as a command line argument.

perl -F'\t' -lane 'BEGIN{print "<table border=1 cellpadding=3 cellspacing=0>"}print "<tr>", (map {"<td>$_</td>"} @F), "</tr>";END{print "</table>}'

The map is in parentheses so that the closing '<tr>' tag is not slurped in as part of it's input array.

Perl subroutine references

I just found this useful for generating a dispatch/lookup table. You can create a hash table with the values being references to subroutines.

Here's a simple example:

> perl -le '$a = sub { 5 * $_[0]};print &{$a}(23);'
> 115

A better example is to use this as a look-up table. Here's another simple example:

%table = (
 "+" => sub { $_[0] + $_[1] },
 "-" => sub { $_[0] - $_[1] },
 "*" => sub { $_[0] * $_[1] },
 "/" => sub { $_[0] / $_[1] },
);

print &{$table{"+"}}(12,24), "\n";
print &{$table{"-"}}(24,12)), "\n";

This would output 36 and 12 respectively. This is very handy for more complex processing and parsing (which is what I'm using it for).

running command line perl within a bash script

Maybe it's just me, but this is something I've struggled with on a couple of occasions.

Since I can't give any of the examples I'm actually working on, I'll have to use something which is less obviously useful.

The simple version is to use bash to loop through some files and use Perl to print out the filename (as stored by the bash script):

for file in `ls *.label`;
   do perl -le "\$a=1;print \"${file} \$a\"";
done

The important things to make this work are:
1. The double quotes used for the Perl script. This enables the variable interpretation by bash.
2. Escape sequences for the double quotes used in the Perl script - the double quotes are necessary to make Perl interpret the Perl variables.
3. Escape sequences for the Perl variables - this distinguishes the Perl variables from the bash ones.

The final script I used was a lot more complicated than this and was used to generate a series of files. I guess I can put the script in as, with no context, it has little meaning.

for si in `seq 38 47`;
 do perl -F',' -lane "if(@F==4)
   {
      print \"\$F[0]\\t\$h{\$F[0]}:\$F[1],\$F[2]\"
        if \$F[3] == $si and \!\$i{\$F[0]}++;
   }
   else{
      @F=split/\t/;
      \$h{\$F[1]} = \$F[0];
   }" file1 file2 > output_${si}.tsv;
done

It would have been nicer just to write a separate Perl script and call that, really. But there you go.