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comp.lang.ruby

shell, ruby and regexp

pere.noel

10/3/2006 6:28:00 AM

over Mac OS X the latest and ruby 1.8.4 i've found strange interferences
between the shell (in my case zsh) and arguments to a ruby script if one
of the args is a Regexp as for examples :

/to.*/ - case 1
/^Tit.*/ - case 2


- case 1 (not the most seriaus) gave an answer from zsh BEFORE any
answer of my ruby script :

~/Desktop%> ruby test_args.rb /to.*/
zsh: no matches found: /to.*/

- case 2 seems to be DANGEROUS because it gaves me a kot of unexepected
args :

~/Desktop%> ruby test_args.rb /^Tit.*/
/Applications/
/Developer/
/Library/
/Network/
/System/
/Users/
/Volumes/
/automount/
/bin/
/cores/
/dev/
/etc/
/opt/
/private/
/sbin/
/tmp/
/usr/
/var/


Notice i've discovered that when designing a small script in order to
delete files )))

Obviously i've found a workaround using quotes around the regexp :

~/Desktop%> ruby test_args.rb "to.*"

but in that case i need another arg to my script in order to tell ruby
it is a regular expression.

did someone have the same quirk ?
--
une bévue
9 Answers

Paul Lutus

10/3/2006 6:48:00 AM

0

Une bévue wrote:

> over Mac OS X the latest and ruby 1.8.4 i've found strange interferences
> between the shell (in my case zsh) and arguments to a ruby script if one
> of the args is a Regexp as for examples :
>
> /to.*/ - case 1
> /^Tit.*/ - case 2
>
>
> - case 1 (not the most seriaus) gave an answer from zsh BEFORE any
> answer of my ruby script :
>
> ~/Desktop%> ruby test_args.rb /to.*/
> zsh: no matches found: /to.*/

This is a classic error in the use of a shell. You need to understand that
your typing is interpreted first by the shell, and only then by Ruby.

>
> - case 2 seems to be DANGEROUS because it gaves me a kot of unexepected
> args :
>
> ~/Desktop%> ruby test_args.rb /^Tit.*/
> /Applications/
> /Developer/
> /Library/
> /Network/
> /System/
> /Users/
> /Volumes/
> /automount/
> /bin/
> /cores/
> /dev/
> /etc/
> /opt/
> /private/
> /sbin/
> /tmp/
> /usr/
> /var/
>
>
> Notice i've discovered that when designing a small script in order to
> delete files )))
>
> Obviously i've found a workaround using quotes around the regexp :
>
> ~/Desktop%> ruby test_args.rb "to.*"
>
> but in that case i need another arg to my script in order to tell ruby
> it is a regular expression.

What's wrong with the original string enclosed in quotes?

Instead of:

ruby test_args.rb /to.*/

Type this instead:

ruby test_args.rb "/to.*/"

>
> did someone have the same quirk ?

I need to tell you something. Everyone who uses any variation on Unix (Unix,
Linux, etc.) learns this right away about shell sessions.

The solution is to get into the habit of using "irb" for little experiments,
and writing a formal scripts for big experiments. Avoid typing things into
the shell that it will interpret as wildcards.

--
Paul Lutus
http://www.ara...

pere.noel

10/3/2006 7:03:00 AM

0

Paul Lutus <nospam@nosite.zzz> wrote:

>
> What's wrong with the original string enclosed in quotes?
>
> Instead of:
>
> ruby test_args.rb /to.*/
>
> Type this instead:
>
> ruby test_args.rb "/to.*/"

ok i've done THE MISTAKE to rememeber zsh as a priority over ruby )))

my answer to "What's wrong with the original string enclosed in quotes?"

that didn't work, my script sees it as a string and even if (for this
arg and if enclosed with //) :

this_arg=Regexp.new(this_arg)

then if this arg = "/to.*/"

i get :

puts this_arg.source # (after Regexp.new)

# => /to.*/ INSTEAD OF to.*


the reason why i make no use of // for a regexp arg then i'm obliged to
have another arg yelling if this arg is or not a regexp.

may be here i've missed something too...
--
une bévue

MonkeeSage

10/3/2006 7:10:00 AM

0


Une bévue wrote:
> that didn't work, my script sees it as a string and even if (for this
> arg and if enclosed with //) :
>
> this_arg=Regexp.new(this_arg)
>
> then if this arg = "/to.*/"
>
> i get :
>
> puts this_arg.source # (after Regexp.new)
>
> # => /to.*/ INSTEAD OF to.*

this_arg=Regexp.new(this_arg[1..-2])

Regards,
Jordan

pere.noel

10/3/2006 7:18:00 AM

0

MonkeeSage <MonkeeSage@gmail.com> wrote:

>
> this_arg=Regexp.new(this_arg[1..-2])

clever idae, thanks again !!!
--
une bévue

Eero Saynatkari

10/3/2006 7:28:00 AM

0

On 2006.10.03 16:05, Une b?vue wrote:
> Paul Lutus <nospam@nosite.zzz> wrote:
>
> >
> > What's wrong with the original string enclosed in quotes?
> >
> > Instead of:
> >
> > ruby test_args.rb /to.*/
> >
> > Type this instead:
> >
> > ruby test_args.rb "/to.*/"
>
> ok i've done THE MISTAKE to rememeber zsh as a priority over ruby )))
>
> my answer to "What's wrong with the original string enclosed in quotes?"
>
> that didn't work, my script sees it as a string and even if (for this
> arg and if enclosed with //) :

Everything you get in ARGV is a String. You cannot create Ruby
objects outside Ruby.

> this_arg=Regexp.new(this_arg)
>
> then if this arg = "/to.*/"
>
> i get :
>
> puts this_arg.source # (after Regexp.new)
>
> # => /to.*/ INSTEAD OF to.*

You have a few choices. You can pass in '/to.*/' and strip off the /'s,
you can #eval it or you could pass in 'to.*' instead and then interpolate
or Regexp.new it.

Michael Fellinger

10/3/2006 8:06:00 AM

0

On Tuesday 03 October 2006 16:05, Une bévue wrote:
> Paul Lutus <nospam@nosite.zzz> wrote:
> > What's wrong with the original string enclosed in quotes?
> >
> > Instead of:
> >
> > ruby test_args.rb /to.*/
> >
> > Type this instead:
> >
> > ruby test_args.rb "/to.*/"
>
> ok i've done THE MISTAKE to rememeber zsh as a priority over ruby )))
>
> my answer to "What's wrong with the original string enclosed in quotes?"
>
> that didn't work, my script sees it as a string and even if (for this
> arg and if enclosed with //) :
>
> this_arg=Regexp.new(this_arg)
>
> then if this arg = "/to.*/"
>
> i get :
>
> puts this_arg.source # (after Regexp.new)
>
> # => /to.*/ INSTEAD OF to.*

Regexp.new('/.*rb/'[%r(/(.*?)/), 1])
# /.*rb/

>
>
> the reason why i make no use of // for a regexp arg then i'm obliged to
> have another arg yelling if this arg is or not a regexp.
>
> may be here i've missed something too...

Robert Klemme

10/3/2006 8:46:00 AM

0

"Une bévue" <pere.noel@laponie.com.invalid> wrote:
> ok i've done THE MISTAKE to rememeber zsh as a priority over ruby )))

It's not so much a "priority" as simple order of things happening (you can
read that on each shell's man page): first a command line undergoes various
substitutions (these change between shells and syntax used in the command
line), only *then* the result of these subsitutions is handed off to the
process forked (or shell internal command).

> my answer to "What's wrong with the original string enclosed in
> quotes?"
>
> that didn't work, my script sees it as a string and even if (for this
> arg and if enclosed with //) :

The point is, your script sees *every* argument as string. There is no
other type of arguments for process execs. If you need conversion, you have
to do it yourself. For example

ARGV.map! do |arg|
case arg
when %r{\A/.*/[io]*\z}
eval arg
when %r{[+-]?\d+}
arg.to_i
else
arg
end
end

> may be here i've missed something too...

I guess you were mindset that there needs to be some mechanism to
automatically convert process arguments for you. That does not exist - at
least not in Ruby.

Kind regards

robert

pere.noel

10/3/2006 9:18:00 AM

0

Robert Klemme <shortcutter@googlemail.com> wrote:

>
> ARGV.map! do |arg|
> case arg
> when %r{\A/.*/[io]*\z}
> eval arg
> when %r{[+-]?\d+}
> arg.to_i
> else
> arg
> end
> end
>
> > may be here i've missed something too...
>
> I guess you were mindset that there needs to be some mechanism to
> automatically convert process arguments for you.

not exactly because i was doing a :

arg = Regex.new(arg)...
--
une bévue

Gerard

8/21/2011 9:49:00 PM

0

M forever wrote:
> On Aug 21, 4:57 pm, "Gerard" <ghe_no_spam_ndrik...@hotmail.com> wrote:
> > M forever wrote:
> > > On Aug 21, 4:24 pm, "Gerard" <ghe_no_spam_ndrik...@hotmail.com>
> > > wrote:
> > > > It never stops, such a FM forever.
> > > > (Must be an very old-fashioned one, because it says that it goes
> > > > "offline".)
> >
> > > We already know that "it never stops" because you keep obsessively
> > > "replying" to and "commenting" on everything I write here. You
> > > can't stop.
> >
> > > My question still is, why is that? Why do you "reply" to
> > > everything I and other write even though you kow you are either
> > > ignored or scorned? What is the point?
> >
> > See?
> > It never stops.
> > It's a FM forever. A broken record.
>
> Why can't you give me an answer? With every one of these pointless
> "replies", you confirm what I just said.

See?
It never stops.
It's a FM forever. A broken record.
Without memory also.