From: Martin DeMello <martindemello@...>
Date: 2007-03-13T17:36:20+09:00
Subject: Re: perl to ruby

On 3/13/07, Jan Svitok <jan.svitok@gmail.com> wrote:
> On 3/13/07, Marcin Kulisz <marcin.kulisz@gmail.com> wrote:
> > hi all,
> > today is my first day with ruby and I'm trying to rewrite a few of my
> > scripts from perl to ruby & it's not too easy. can anyone help me with
> > script below. I've done a few thinks but when one is working another
> > don't.
>
> #!/usr/bin/ruby -w
>
> usr = ARGV[0]
> id = `cat /etc/passwd|grep #{usr}|cut -d\":\" -f3`.to_i

And in pure ruby,

id = IO.readlines('/etc/passwd').grep(/#{usr}/).first.split(/:/).at(2).to_i

or for efficiency

File.open("/etc/passwd", "r") {|f| id =
f.grep(/#{usr}/).first.split(/:/).at(2).to_i}

which doesn't read the whole file into an array first.

Also, ideally grep(/#{usr}/) should be
grep(Regexp.new(Regexp.quote(usr))), in case usr contains
special-to-the-regexp-engine characters.

martin