A shorter regexp?

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Hi, all.

Sorry to've ignited such a firestorm with my questions regarding stat() vs
ls for file dating... ;-)) I hope this question will be less provocative.

At one point in my script, I still use ls to get a line of data for files,
what I'm trying for is a regexp that'll pull the filename out--including
soft links. What I have right now--while it works--is rather, um, long:

$line =~
/^[-l][-rswx]{9}\s+\d+\s+\w+\s+\w+\s+\d+\s+\w+\s+\d+\s+(?:\d {4}|\d\d:\d\d)\s+(.*)$/;

I had a shorter regexp, actually *much* shorter:

$line =~ /^.+(?:\d{4}|\d\d:\d\d)\s+(.*)$/;

but it ran into a problem with the following file line:

lrwxrwxrwx ... Sep 10 15:15 1614 -> /opt/K/SCO/...1614

It tripped on the 1614 and returned only "-> /opt/K/SCO/...1614" as the
filename. Anyone have any suggestions for shortening that monster regexp
listed above?

Thanks!

Deane
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Hi, all.



Sorry to've ignited such a firestorm with my questions regarding stat() vs ls for file dating... ;-))  I hope this question will be less provocative.



At one point in my script, I still use ls to get a line of data for files, what I'm trying for is a regexp that'll pull the filename out--including soft links. What I have right now--while it works--is rather, um, long:



$line =~

/^[-l][-rswx]{9}\s+\d+\s+\w+\s+\w+\s+\d+\s+\w+\s+\d+\s+(?:\d {4}|\d\d:\d\d)\s+(.*)$/;



I had a shorter regexp, actually *much* shorter:



$line =~ /^.+(?:\d{4}|\d\d:\d\d)\s+(.*)$/;



but it ran into a problem with the following file line:



lrwxrwxrwx ... Sep 10 15:15 1614 -> /opt/K/SCO/...1614



It tripped on the 1614 and returned only "-> /opt/K/SCO/...1614" as the filename. Anyone have any suggestions for shortening that monster regexp listed above?



Thanks!



Deane
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RE: A shorter regexp?

Not shorter, but maybe more readable :-)
This is a regex I have to match "ls -la" output on
Unix/Linux/Cygwin systems for directories, files,
and symlinks.

/^
([-dl]\S{9}) # perms
(\+)?\s+ # access control list present
(\d+)\s+ # number of links
(\S+)\s+ # owner
(\S+)\s+ # group
(\d+)\s+ # size
([A-Z][a-z][a-z]\s+\d\d?\s+(?:\d\d:\d\d|\d{4,}))\s # mtime
(.*?) # name
(?:\s+->\s(.*))? # symlink target
$/x;

--
Mike Arms


-----Original Message-----
From: Deane.Rothenmaier@walgreens.com
[mailto:Deane.Rothenmaier@walgreens.com]
Sent: Friday, October 01, 2004 2:12 PM
To: activeperl@listserv.ActiveState.com
Subject: A shorter regexp?


Hi, all.

Sorry to've ignited such a firestorm with my questions regarding stat() vs
ls for file dating... ;-)) I hope this question will be less provocative.

At one point in my script, I still use ls to get a line of data for files,
what I'm trying for is a regexp that'll pull the filename out--including
soft links. What I have right now--while it works--is rather, um, long:

$line =~
/^[-l][-rswx]{9}\s+\d+\s+\w+\s+\w+\s+\d+\s+\w+\s+\d+\s+(?:\d {4}|\d\d:\d\d)\s
+(.*)$/;

I had a shorter regexp, actually *much* shorter:

$line =~ /^.+(?:\d{4}|\d\d:\d\d)\s+(.*)$/;

but it ran into a problem with the following file line:

lrwxrwxrwx ... Sep 10 15:15 1614 -> /opt/K/SCO/...1614

It tripped on the 1614 and returned only "-> /opt/K/SCO/...1614" as the
filename. Anyone have any suggestions for shortening that monster regexp
listed above?

Thanks!

Deane

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RE: A shorter regexp?

> At one point in my script, I still use ls to get a line of data for
> files, what I'm trying for is a regexp that'll pull the filename
> out--including soft links. What I have right now--while it works--is
> rather, um, long:
>
> $line =~ /^[-l][-rswx]{9}\s+\d+\s+\w+\s+\w+\s+\d+\s+\w+\s+\d+\s+
> (?:\d{4}|\d\d:\d\d)\s+(.*)$/;
>
> I had a shorter regexp, actually *much* shorter:
>
> $line =~ /^.+(?:\d{4}|\d\d:\d\d)\s+(.*)$/;
>
> but it ran into a problem with the following file line:
>
> lrwxrwxrwx ... Sep 10 15:15 1614 -> /opt/K/SCO/...1614

Deane,

Just taking a quick look, and ignoring a whole host of assumptions, it seems
like you're looking for everything after the date:

$line = 'lrwxrwxrwx ... Sep 10 15:15 1614 -> /opt/K/SCO/...1614';
$line =~ /\w{3} \d+ \d+:\d+ (.*)$/;
print $1;

Chris


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Re: A shorter regexp?

Deane.Rothenmaier@walgreens.com wrote:

>At one point in my script, I still use ls to get a line of data for files,
>what I'm trying for is a regexp that'll pull the filename out--including
>soft links. What I have right now--while it works--is rather, um, long:
>
>$line =~
>/^[-l][-rswx]{9}\s+\d+\s+\w+\s+\w+\s+\d+\s+\w+\s+\d+\s+(?:\ d{4}|\d\d:\d\d)\s+(.*)$/;
>
>I had a shorter regexp, actually *much* shorter:
>
>$line =~ /^.+(?:\d{4}|\d\d:\d\d)\s+(.*)$/;
>
The long ls on my machine looks like it's a fixed format. It's 53
characters from the line start to the first character of the time, so
start the regexp with the exact number of "any" characters :

$line =~ /^.{52}(\d\d:\d\d)\s+(.*)$/;

Either that or use unpack:
my ($time, $name) = unpack("x52a5xa*", $line);

>
>but it ran into a problem with the following file line:
>
>lrwxrwxrwx ... Sep 10 15:15 1614 -> /opt/K/SCO/...1614
>
>It tripped on the 1614 and returned only "-> /opt/K/SCO/...1614" as the
>filename. Anyone have any suggestions for shortening that monster regexp
>listed above?
>
>


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RE: A shorter regexp?

Todd Beverly [todd.beverly@kodak.com] wrote:
>Deane.Rothenmaier@walgreens.com wrote:
>>At one point in my script, I still use ls to get a line of data for files,

>>what I'm trying for is a regexp that'll pull the filename out--including
>>soft links. What I have right now--while it works--is rather, um, long:
>>
>>$line =~
>>/^[-l][-rswx]{9}\s+\d+\s+\w+\s+\w+\s+\d+\s+\w+\s+\d+\s+(?: \d{4}|\d\d:\d\d)
\s+(.*)$/;
>>
>>I had a shorter regexp, actually *much* shorter:
>>
>>$line =~ /^.+(?:\d{4}|\d\d:\d\d)\s+(.*)$/;
>>
>The long ls on my machine looks like it's a fixed format. It's 53
>characters from the line start to the first character of the time, so
>start the regexp with the exact number of "any" characters :
>
>$line =~ /^.{52}(\d\d:\d\d)\s+(.*)$/;
>
>Either that or use unpack:
>my ($time, $name) = unpack("x52a5xa*", $line);
>
>>
>>but it ran into a problem with the following file line:
>>
>>lrwxrwxrwx ... Sep 10 15:15 1614 -> /opt/K/SCO/...1614
>>
>>It tripped on the 1614 and returned only "-> /opt/K/SCO/...1614" as the
>>filename. Anyone have any suggestions for shortening that monster regexp
>>listed above?

First off, I think Todd is off on his 53 characters (at least
from my tests). My test shows that the HH:MM of the mtime starts
at 51 characters in. This is true for Cygwin, Solaris, and Linux.

> ls -l z
-rw-rw-r-- 1 marms marms 30 Sep 3 16:01 z
1 2 3 4 5 6
123456789012345678901234567890123456789012345678901234567890

Also, if you have a big file (over 99,999,999 bytes), you will
find that the size gets jammed in and upsets the nice columns.
Thus for big files, the HH:MM will start later (depending on how
many extra digits it takes to represent the file size):

> ls -l TheOpenCD-v1.4.iso.zip TheOpenCD-v1.4.iso.zip.md5
-r--r--r-- 1 marms marms 279681009 May 3 14:53
TheOpenCD-v1.4.iso.zip
-r--r--r-- 1 marms marms 57 May 3 14:53
TheOpenCD-v1.4.iso.zip.md5
1 2 3 4 5 6
123456789012345678901234567890123456789012345678901234567890

So this solution is not safe.

--
Mike Arms

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RE: A shorter regexp?

Deane.Rothenmaier@walgreens.com wrote:
> Hi, all.
>
> Sorry to've ignited such a firestorm with my questions regarding
> stat() vs ls for file dating... ;-)) I hope this question will be
> less provocative.
>
> At one point in my script, I still use ls to get a line of data for
> files, what I'm trying for is a regexp that'll pull the filename
> out--including soft links. What I have right now--while it works--is
> rather, um, long:
>
> $line =~
>
/^[-l][-rswx]{9}\s+\d+\s+\w+\s+\w+\s+\d+\s+\w+\s+\d+\s+(?:\d {4}|\d\d:\d\
d)\s+(.*)$/;
>
> I had a shorter regexp, actually *much* shorter:
>
> $line =~ /^.+(?:\d{4}|\d\d:\d\d)\s+(.*)$/;
>
> but it ran into a problem with the following file line:
>
> lrwxrwxrwx ... Sep 10 15:15 1614 -> /opt/K/SCO/...1614
>
> It tripped on the 1614 and returned only "-> /opt/K/SCO/...1614" as
> the filename. Anyone have any suggestions for shortening that monster
> regexp listed above?

If you are using the GNU ls, then you could use the -Q switch to quote
the file name(s), which should make them easier to locate with a regex,
or possibly Text::Balanced.

However, I don't know why you would want to use ls and a regex. The
following seems easier and more reliable to me:

foreach (<*>) {
print $_;
print " -> ", readlink if -l;
print "\n";
}

HTH

--
Brian Raven



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