Platinum Partner
php,perl,tips and tricks

Learn Just One Perl Command

A while back I wrote a post Learn one sed command. In a nutshell, I said it’s worth learning sed just do commands of the form sed s/foo/bar/ to replace “foo” with “bar.”

Dan Haskin and Will Fitzgerald suggested in their comments that instead of sed use perl -pe with the same command. The advantage is that you could use Perl’s more powerful regular expression syntax. Will said he uses Perl like this:

cat file | perl -pe "s/old/new/g" > newfile

I think they’re right. Except for the simplest regular expressions, sed’s regular expression syntax is too restrictive. For example, I recently needed to remove commas that immediately follow a digit and this did the trick:

cat file | perl -pe "s/(?<=\d),//g" > newfile

Since sed does not have the look-behind feature or \d for digits, the corresponding sed code would be more complicated.

I quit writing Perl years ago. I don’t miss Perl as a whole, but I do miss Perl’s regular expression support.

Learning Perl is a big commitment, but just learning Perl regular expressions is not. Perl is the leader in regular expression support, and many programming languages implement a subset of Perl’s regex features. You could just use a subset of Perl features you already know, but you’d have the option of using more features.




Published at DZone with permission of {{ articles[0].authors[0].realName }}, DZone MVB. (source)

Opinions expressed by DZone contributors are their own.

{{ tag }}, {{tag}},

{{ parent.title || parent.header.title}}

{{ parent.tldr }}

{{ parent.urlSource.name }}
{{ parent.authors[0].realName || parent.author}}

{{ parent.authors[0].tagline || parent.tagline }}

{{ parent.views }} ViewsClicks
Tweet

{{parent.nComments}}