I have two strings: $dir1 and $dir2. I want to use chdir as shown below:
chdir "/home/$dir1/$dir2";
when I try this it doesn't change the directory. I checked the current working directory same as before
Is there any way to do this?
Typically I write that as:
use v5.10;
use File::Spec::Functions;
my $dir = catfile( '/home', $dir1, $dir2 );
die "Dir <$dir> isn't a directory or doesn't exist" unless -e -d $dir;
chdir $dir or die "Could not change to <$dir>: $!";
Whenever you do something with the system, check the results to ensure it happened.
And, curiously, I didn't realize that Pearson's sample chapter of my book Effective Perl Programming is the one that covers stacked file test operators.
Related
I am trying to do cd in my perl script. I am using the below command:
chdir "/home/test/test1/test2/perl*";
perl* value is actually perl_0122_2044, but this value may vary.
The above chdir command is not doing cd to the path. Am I doing something wrong?
chdir does not accept * and other expansion characters in the argument. Use glob or something similar for this to extract a single directory, then chdir to that. For example, this changes directory to the first /home/test/test1/test2/perl* it finds:
$dir = (glob "/home/test/test1/test2/perl*")[0];
# only change dir if any dir was found:
if (-d $dir) {
# fail if cannot change dir (or, even better, use autodie):
chdir $dir or die "Could not change to $dir: $!";
}
chdir expects a path, not a wildcard. Use glob to expand the wildcard:
my ($dir) = glob "/home/test/test1/test2/perl*";
chdir $dir or die "$dir: $!";
If there are multiple expansions, the first one will be used.
In similar vein, glob is handled by a module in raku https://modules.raku.org/dist/IO::Glob
I have a directory which contains multiple levels of sub dirs. I want to print path for each and every directory.
Currently, I am using
use File::Find;
find(
{
wanted => \&findfiles,
}, $maindirectory);
sub findfiles
{
if (-d) {
push #arrayofdirs,$File::Find::dir;
}
}
But each subdirectory contains thousands of files at each level. The above code takes lot of time to provide the result as it compares each file for directory. Is there a way to get subdirectories path without comparing files to save time or any other optimized method?
Edit: This issue got partially resolved but a new issue came up because of this solution. I have listed it here: Multiple File search in varying level of directories in perl
If you are on a UNIX/Linux platform then you can try reading output of find $maindirectory -type d command into your program (see this answer for a safe way to do that.). This command prints the names of directories in $maindirectory. It is faster because a compiled C program (find) does all the hard work. The following script should print all directory paths found.
Sample script:
use strict;
use warnings;
my $maindirectory = '.';
open my $fh, '-|', 'find', $maindirectory, '-type', 'd' or die "Can't open pipe: $!";
while( my $dir = <$fh>) {
print $dir;
}
close $fh or warn "can't close pipe: $!";
Note that there is no point in calling find through perl and then just printing its output without any processing. You can just as well run find $maindirectory -type d in shell itself.
I'm trying to write a script that prints out the file structure starting at the folder the script is located in. The script works fine without the recursive call but with that call it prints the contents of the first folder and crashes with the following message: closedir() attempted on invalid dirhandle DIR at printFiles.pl line 24. The folders are printed and the execution reaches the last line but why isn't the recursive call done? And how should I solve this instead?
#!/usr/bin/perl -w
printDir(".");
sub printDir{
opendir(DIR, $_[0]);
local(#files);
local(#dirs);
(#files) = readdir(DIR);
foreach $file (#files) {
if (-f $file) {
print $file . "\n";
}
if (-d $file && $file ne "." && $file ne "..") {
push(#dirs, $file);
}
}
foreach $dir (#dirs) {
print "\n";
print $dir . "\n";
printDir($dir);
}
closedir(DIR);
}
You should always use strict; and use warnings; at the start of your Perl program, especially before you ask for help with it. That way Perl will show up a lot of straightforward errors that you may not notice otherwise.
The invalid filehandle error is likely because DIR is a global directory handle and has been closed already by a previous execution of the subroutine. It is best to always used lexical handles for both files and directories, and to test the return code to make sure the open succeeded, like this
opendir my $dh, $_[0] or die "Failed to open $_[0]: $!";
One advantage of lexical file handles is that they are closed implicitly when they go out of scope, so there is no need for your closedir call at the end of the subroutine.
local isn't meant to be used like that. It doesn't suffice as a declaration, and you are creating a temporary copy of a global variable that everything can access. Best to use my instead, like this
my #dirs;
my #files = readdir $dh;
Also, the file names you are using from readdir have no path, and so your file tests will fail unless you either chdir to the directory being processed or append the directory path string to the file name before testing it.
Use the File::Find module. The way i usually do this is using the find2perl tool which comes with perl, which takes the same parameters as find and creates a suitable perl script using File::Find. Then i fine-tune the generated script to do what i want it to do. But it's also possible to use File::Find directly.
Why not use File::Find?
use strict; #ALWAYS!
use warnings; #ALWAYS!
use File::Find;
find(sub{print "$_\n";},".");
I'm writing a script in perl strawberry. The first thing it needs to be able to do is take a path argument and get a directory listing for that path, and it needs to be able to distinguish between files and folders. I read some tutorials on the subject and wrote the script below, but it only works when I give it the path that the script is currently residing in. If I give it any other path, the -f and -d tests don't work.
EDIT: Clarification: The script DOES put all the files and folders into #thefiles if I give it a path other than it's own, it's just the -f and -d tests that don't work.
use Getopt::Long;
my $dir;
GetOptions('-d=s' => \$dir);
opendir(DIR, $dir) or die "BORKED";
#thefiles = readdir(DIR);
print DIR;
closedir(DIR);
#filez;
#dirz;
foreach $file (#thefiles){
if (-f$file){
push(#filez, $file);
}
if (-d$file){
push(#dirz, $file);
}
}
print "files: #filez \n";
print "Directories: #dirz \n";
Here's a screenshot: http://i.stack.imgur.com/RMmFz.jpg
Hope someone can help and thanks very much for your time. :)
martin clayton told you the reason your code does not work.
Here is a way to fix it using map and some more modern Perl constructs:
use strict;
use warnings;
use Getopt::Long;
my $dir;
GetOptions('-d=s' => \$dir);
opendir my $dh, $dir or die "BORKED: $!";
my #thefiles = map { "$dir/$_" } readdir $dh;
closedir $dh;
my #filez;
my #dirz;
for my $file (#thefiles) {
push #filez, $file if -f $file;
push #dirz , $file if -d $file;
}
print "files: #filez \n";
print "Directories: #dirz \n";
It's because the filetest -f and -d operators use a relative path unless you provide an absolute one. The readdir function will return the file (and subdirectory...) names found in the directory, but not the full paths.
From the docs:
If you're planning to filetest the
return values out of a readdir, you'd
better prepend the directory in
question. Otherwise, because we didn't
chdir there, it would have been
testing the wrong file.
If you have a path to a file (for example, /home/bob/test/foo.txt) where each subdirectory in the path may or may not exist, how can I create the file foo.txt in a way that uses "/home/bob/test/foo.txt" as the only input instead of creating every nonexistent directory in the path one by one and finally creating foo.txt itself?
You can use File::Basename and File::Path
use strict;
use File::Basename;
use File::Path qw/make_path/;
my $file = "/home/bob/test/foo.txt";
my $dir = dirname($file);
make_path($dir);
open my $fh, '>', $file or die "Ouch: $!\n"; # now go do stuff w/file
I didn't add any tests to see if the file already exists but that's pretty easy to add with Perl.
Use make_dir from File::Util
use File::Util;
my($f) = File::Util->new();
$f->make_dir('/var/tmp/tempfiles/foo/bar/');
# optionally specify a creation bitmask to be used in directory creations
$f->make_dir('/var/tmp/tempfiles/foo/bar/',0755);
I don't think there's a standard function that can do all of what you ask, directly from the filename.
But mkpath(), from the module File::Path, can almost do it given the filename's directory. From the File::Path docs:
The "mkpath" function provides a
convenient way to create directories,
even if your "mkdir" kernel call won't
create more than one level of
directory at a time.
Note that mkpath() does not report errors in a nice way: it dies instead of just returning zero, for some reason.
Given all that, you might do something like:
use File::Basename;
use File::Path;
my $fname = "/home/bob/test/foo.txt";
eval {
local $SIG{'__DIE__'}; # ignore user-defined die handlers
mkpath(dirname($fname));
};
my $fh;
if ($#) {
print STDERR "Error creating dir: $#";
} elsif (!open($fh, ">", $fname)) {
print STDERR "Error creating file: $!\n";
}