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From: viktor@cucumber.Princeton.EDU (Viktor Dukhovni)
Newsgroups: comp.lang.perl
Subject: Re: How about building in directory-tree-walking? like "ftw()"
Message-ID: <14767@phoenix.Princeton.EDU>
Date: 23 Mar 90 06:34:52 GMT
References: <39362@iuvax.cs.indiana.edu> <7514@jpl-devvax.JPL.NASA.GOV>
Sender: news@phoenix.Princeton.EDU
Distribution: comp
Lines: 89

lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall) writes:


>On the other hand, you can just mutate the following into what you want.
>This actually runs faster than find on my system, but that's because it's
>only looking at the names in leaf directories, not the inode.  It also
>assumes that directory link counts work in the standard fashion.

	How did you know I was writing a fast tree symbolic copy? :-)
With a modified version of dodir,  it got even faster,  Thanks.

	And by the way here is a program that when duplicating
large trees does a lot of mkdirs!  Though forking once for 100
directories seems not too expensive.

---------------------------------------
#! /usr/bin/perl

( $#ARGV != 1 )       &&
    die "Usage: $0 <src> <dst>\n" ;

($tail=$src=shift) !~ m,^/, &&
    die "Use full src path name\n" ;

($dst=shift) !~ m,^/, &&
    die "Use full dst path name\n" ;

$tail =~ s,.*/,, ;
$dst .= "/$tail" if ( -d $dst  && ! ($dst =~ m,/$tail$,) );

if ( ! -d "$dst" ) {
    system "mkdir",$dst ; die "\n" if $? ;
}

chdir($src) || die "Could not chdir to $src\n" ;
$np = $nd = 0 ;
&dodir("",0);

chdir($dst) || die "Could not chdir to $dst\n" ;

while( $#dirs >= $[ ) {
    system("mkdir",splice(@dirs,-100,100)) ;
    die "\n" if $?;
}

for(@pathnames) {
    symlink($src."/".$_,$_) || die "$_: symlink failed\n";
}

;;
;;
;;
sub dodir {
    local($dir,$nlink) = @_;
    local($dev,$ino,$mode);
    ($dev,$ino,$mode,$nlink) = stat('.') unless $nlink;	# first time

    opendir(DIR,'.') || die "Can't open $dir";
    local(@filenames) = readdir(DIR);
    closedir(DIR);

    if ($nlink == 2) {			# this dir has no subdirectories
	for(@filenames) {
	    $pathnames[$np++] = "$dir$_" if ( $_ ne '.' && $_ ne '..' );
	}
    }
    else {				# this dir has subdirectories
	for (@filenames) {
	    next if $_ eq '.';
	    next if $_ eq '..';
	    $name = "$dir$_";

	    ($dev,$ino,$mode,$nlink) = stat($_);
	    if (($mode & 0170000) != 0040000) {
	        $pathnames[$np++] = $name ;
		next;
	    }
	    $dirs[$nd++] = $name ;

	    chdir $_ || die "Can't cd to $name";
	    &dodir($name."/",$nlink);
	    chdir '..';
	}
    }
}
	Viktor Dukhovni <viktor@math.princeton.edu>	: ARPA
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