perl to ruby

[Marcin Kulisz]

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/perl -w

$usr=$ARGV[0];
$id=`cat /etc/passwd|grep $usr|cut -d\":\" -f3`;
if ($id>=1000){
$text=`finger $usr`;
$text=~s/\n/\<br\>/g;
print $text;
} else {
print "wal się na ryj złodzieju";
}

 

[Jan Svitok]

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[Marcin Kulisz]

#!/usr/bin/ruby -w

usr = ARGV[0] ...
puts appends \n, if you don't like it, use print

thx a lot, I was very close to it but had probles with grep, first I
tired to do it with command "system" but it doesn't working then change
my mind & tired with method ".grep" & it doesn't work too but your
solution is easy & lovely
again thx for help

 

[Robert Klemme]

#!/usr/bin/ruby -w

usr = ARGV[0] ..
puts appends \n, if you don't like it, use print

thx a lot, I was very close to it but had probles with grep, first I
tired to do it with command "system" but it doesn't working then change
my mind & tired with method ".grep" & it doesn't work too but your
solution is easy & lovely
again thx for help

Also look at this:

http://raa.ruby-lang.org/project/etc/

Kind regards

robert

 

[Marcin Kulisz]

Also look at this:

http://raa.ruby-lang.org/project/etc/

hehe thx, I read about it but sometimes my memory is too short

 

[Martin DeMello]

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

 

[Martin DeMello]

For efficiency, wouldn't using the Etc module would be best?

require 'etc'
user = ARGV[0] or abort "missing user name"
puts (if (Etc.getpwnam(user)).uid >= 1000

touche'

martin

 

[Eckie Silapaswang]

#!/usr/bin/ruby -w

usr = ARGV[0] ...
puts appends \n, if you don't like it, use print

thx a lot, I was very close to it but had probles with grep, first I
tired to do it with command "system" but it doesn't working then change
my mind & tired with method ".grep" & it doesn't work too but your
solution is easy & lovely
again thx for help

Just for future reference (and I found this out the hard way by having
it not working on me either) the
system("insert_your_shell_command_here") method will return a boolean if
your shell can execute the command (1 or 0, true or false). You can use
the grep command, but as you saw in the solution, you use backticks ` `
to have system commands in your ruby script.

Best regards,

Eckie

 

[Chad Perrin]

or for efficiency

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

. . or for more readability:

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

I'm sure greater readability can be had by rewriting that entirely, but
I found the multiline braces approach suboptimal, personally. YMMV.

One could also split up that string of methods into more than one line
via assignment to variables, but I'm lazy enough to prefer to spend
twice as much effort talking about why I didn't.

 

[Martin DeMello]

. . . or for more readability:

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

I'm sure greater readability can be had by rewriting that entirely, but
I found the multiline braces approach suboptimal, personally. YMMV.

And the fact that my paste put a line break where it did didn't help
that was supposed to be on one line - didn't realise how long it
had gotten.

m.

 

[Chad Perrin]

And the fact that my paste put a line break where it did didn't help
that was supposed to be on one line - didn't realise how long it
had gotten.

Hmm. It should have occurred to me that was meant to be all one line.

I think lines that long should usually be broken up for readability
anyway. Usually.

 

[Rob Biedenharn]

And the fact that my paste put a line break where it did didn't help
that was supposed to be on one line - didn't realise how long it
had gotten.

Hmm. It should have occurred to me that was meant to be all one line.

I think lines that long should usually be broken up for readability
anyway. Usually.

--
CCD CopyWrite Chad Perrin [ http://ccd.apotheon.org ]
"The first rule of magic is simple. Don't waste your time waving your
hands and hopping when a rock or a club will do." - McCloctnick the
Lucid

File.open("/etc/passwd", "r") do |f|
id = f.detect {|line| line =~ /\A#{usr}:/}.split(/:/)[2].to_i
end

using grep will read all the lines, but detect will stop after
finding the first line for which the block is true. I also suggest
bracketing your regexp with \A (beginning of string) and
':' (separator in /etc/passwd) so searching for, say, "0", doesn't
give you the root account.

You probably also want to rescue exceptions that will arise if the
usr is not found.

-Rob

Rob Biedenharn http://agileconsultingllc.com
(e-mail address removed)