I am working on a script which utilizes files in surrounding directories using a path such as
"./dir/file.txt"
This works fine, as long as the working directory is the one containing the script. However the script is going out to multiple users and some people may not change their working directory and run the script by typing its entire path like this:
./path/to/script/my_script.pl
This poses a problem as when the script tries to access ./dir/file.txt it is looking for the /dir directory in the home directory, and of course, it can't fine it.
I am trying to utilize readdir and chdir to correct the directory if it isn't the right one, here is what I have so far:
my $working_directory = $ENV{PWD};
print "Working directory: $working_directory\n"; #accurately prints working directory
my #directory = readdir $working_directory; #crashes script
if (!("my_script.pl" ~~ #directory)){ #if my_script.pl isnt in #directoryies, do this
print "Adjusting directory so I work\n";
print "Your old directory: $ENV{PWD}\n";
chdir $ENV{HOME}; #make the directory home
chdir "./path/to/script/my_script.pl"; #make the directory correct
print "Your new directory: $ENV{PWD}\n";
}
The line containing readdir crashes my script with the following error
Bad symbol for dirhandle at ./path/to/script/my_script.pl line 250.
which I find very strange because I am running this from the home directory which prints out properly right beforehand and contains nothing to do with the "bad symbol"
I'm open to any solutions
Thank you in advance
The readdir operates with a directory handle, not a path on a string. You need to do something like:
opendir(my $dh, $working_directory) || die "can't opendir: $!";
my #directory = readdir($dh);
Check perldoc for both readdir and opendir.
I think you're going about this the wrong way. If you're looking for a file that's travelling with your script, then what you probably should consider is the FindBin module - that lets you figure out the path to your script, for use in path links.
So e.g.
use FindBin;
my $script_path = $FindBin::Bin;
open ( my $input, '<', "$script_path/dir/file.txt" ) or warn $!;
That way you don't have to faff about with chdir and readdir etc.
I am trying to chdir in perl but I am just not able to get my head around what's going wrong.
This code works.
chdir('C:\Users\Server\Desktop')
But when trying to get the user's input, it doesn't work. I even tried using chomp to remove any spaces that might come.
print "Please enter the directory\n";
$p=<STDIN>;
chdir ('$p') or die "sorry";
system("dir");
Also could someone please explain how I could use the system command in this same situation and how it differs from chdir.
The final aim is to access two folders, check for files that are named the same (eg: if both the folders have a file named "water") and copy the file that has the same name into a third folder.
chdir('$p') tries to change to a directory literally named $p. Drop the single quotes:
chdir($p)
Also, after reading it in, you probably want to remove the newline (unless the directory name really does end with a newline):
$p = <STDIN>;
chomp($p);
But if you are just chdiring to be able to run dir and get the results in your script, you probably don't want to do that. First of all, system runs a command but doesn't capture its output. Secondly, you can just do:
opendir my $dirhandle, $p or die "unable to open directory $p: $!\n";
my #files = readdir $dirhandle;
closedir $dirhandle;
and avoid the chdir and running a command prompt command altogether.
I will use it this way.
chdir "C:/Users/Server/Desktop"
The above works for me
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";},".");
Greetings,
I have the following code and am stuck on how I would proceed to modify it so it will ask for the directory, read all files in the directory, then extract specific strings and ouput to an html file? Thanks in advance.
#!/usr/local/bin/perl
use warnings;
use strict;
use Cwd;
print "Enter filename: "; # Should be Enter directory
my $perlfile =STDIN;
open INPUT_FILE, $perlfile || die "Could not open file: $!";
open OUTPUT, '>out.html' || die "Could not open file: $!";
# Evaluates the file and imports it into an array.
my #comment_array = ;
close(INPUT_FILE);
chomp #comment_array;
#comment_array = grep /^\s*#/g, #comment_array;
my $comment;
foreach $comment (#comment_array) {
$comment =~ /####/; #Pattern match to grab only #s
# Prints comments to screen
Print results in html format
# Writes comments to output.html
Writes results to html file
}
close (OUTPUT);
Take it one step at a time. You have a lot planned, but so far you haven't even changed your prompt string to ask for a directory.
To read the entered directory name, your:
my $perlfile =STDIN;
gives an error (under use strict;). Start by looking that error up (use diagnostics; automates this) and trying to figure out what you should be doing instead.
Once you can prompt for a directory name and print it out, then add code to open the directory and read the directory. Directories can be opened and read with opendir and readdir. Make sure you can read the directory and print out the filenames before going on to the next step.
a good starting point to learn about specific functions (from the cmd line)
perldoc -f opendir
However, your particular problem is answered as follows, you can also use command line programs and pipe them into a string to simplify file handling ('cat') and pattern matching ('grep').
#!/usr/bin/perl -w
use strict;
my $dir = "/tmp";
my $dh;
my #patterns;
my $file;
opendir($dh,$dir);
while ($file = readdir($dh)){
if (-f "$dir/$file"){
my $string = `cat $dir/$file | grep pattern123`;
push #patterns, $string;
}
}
closedir($dh);
my $html = join("<br>",#patterns);
open F, ">out.html";
print F $html;
close F;
Recently there have been a few attackers trying malicious things on my server so I've decided to somewhat "track" them even though I know they won't get very far.
Now, I have an entire directory containing the server logs and I need a way to search through every file in the directory, and return a filename if a string is found. So I thought to myself, what better of a language to use for text & file operations than Perl? So my friend is helping me with a script to scan all files for a certain IP, and return the filenames that contain the IP so I don't have to search for the attacker through every log manually. (I have hundreds)
#!/usr/bin/perl
$dir = ".";
opendir(DIR, "$dir");
#files = grep(/\.*$/,readdir(DIR));
closedir(DIR);
foreach $file(#files) {
open FILE, "$file" or die "Unable to open files";
while(<FILE>) {
print if /12.211.23.200/;
}
}
although it is giving me directory read errors. Any assistance is greatly appreciated.
EDIT: Code edited, still saying permission denied cannot open directory on line 10. I am just going to run the script from within the logs directory if you are questioning the directory change to "."
Mike.
Can you use grep instead?
To get all the lines with the IP, I would directly use grep, no need to show a list of files, it's a simple command:
grep 12\.211\.23\.200 *
I like to pipe it to another file and then open that file in an editor...
If you insist on wanting the filenames, it's also easy
grep -l 12\.211\.23\.200 *
grep is available on all Unix//Linux with the GNU tools, or on windows using one of the many implementations (unxutils, cygwin, ...etc.)
You have to concatenate $dirname with $filname when using files found through readdir, remember you haven't chdir'ed into the directory where those files resides.
open FH, "<", "$dirname/$filname" or die "Cannot open $filname:$!";
Incidentally, why not just use grep -r to recursively search all subdirectories under your log dir for your string?
EDIT: I see your edits, and two things. First, this line:
#files = grep(/\.*$/,readdir(DIR));
Is not effective, because you are searching for zero or more . characters at the end of the string. Since it's zero or more, it'll match everything in the directory. If you're trying to exclude files ending in ., try this:
#files = grep(!/\.$/,readdir(DIR));
Note the ! sign for negation if you're trying to exclude those files. Otherwise (if you only want those files and I'm misunderstanding your intent), leave the ! out.
In any case, if you're getting your die message on line 10, most likely you're hitting a file that has permissions such that you can't read it. Try putting the filename in the die output so you can see which file it's failing on:
open FILE, "$file" or die "Unable to open file: $file";
But as with other answers, and to reiterate: Why not use grep? The unix command, not the Perl function.
This will get the file names you are looking for in perl, and probably do it much faster than running and doing a perl regex.
#files = `find ~/ServerLogs -name "*.log" | xargs grep -l "<ip address>"`'
Although, this will require a *nix compliant system, or Cygwin on Windows.
Firstly get a list of files within your source directory:
opendir(DIR, "$dir");
#files = grep(/\.log$/,readdir(DIR));
closedir(DIR);
And then loop through those files
foreach $file(#files)
{
// file processing code
}
My first suggest would be to use grep instead. The right tool for the job, they say...
But to answer your question:
readdir just returns the filenames from the directory. You'll need to concatenate the directory name and filename together.
$path = "$dirname/$filname";
open FH, $path or die ...
Then you should ignore files that are actually directories, such as "." and "..". After getting the $path, check to see if it's a file.
if (-f $path) {
open FH, $path or die ...
while (<FH>)
BTW, I thought I would throw in a mention for File::Next. To iterate over all files in a directory (recursively):
use Path::Class; # always useful.
use File::Next;
my $files = File::Next::files( dir(qw/path to files/) ); # look in path/to/files
while( defined ( my $file = $files->() ) ){
$file = file( $file );
say "Examining $file";
say "found foo" if $file->slurp =~ /foo/;
}
File::Next is taint-safe.
~ doesn't auto-expand in Perl.
opendir my $fh, '~/' or die("Doin It Wrong"); # Doing It Wrong.
opendir my $fh, glob('~/') and die( "Thats right!" );
Also, if you must use readdir(), make sure you guard the expression thus:
while (defined(my $filename = readdir(DH))) {
...
}
If you don't do the defined() test, the loop will terminate if it finds a file called '0'.
Have you looked on CPAN for log parsers? I searched with 'log parse' and it yielded over 200 hits. Some (probably many) won't be relevant - some may be. It depends, in part, on which web server you are using.
Am I reading this right? Your line 10 that gives you the error is
open FILE, "$file" or die "Unable to open files";
And the $file you are trying to read, according to line 6,
#files = grep(/\.*$/,readdir(DIR));
is a file that ends with zero or more dot. Is this what you really wanted? This basically matches every file in the directory, including "." and "..". Maybe you don't have enough permission to open the parent directory for reading?
EDIT: if you only want to read all files (including hidden ones), you might want to use something like the following:
opendir(DIR, ".");
#files = readdir(DIR);
closedir(DIR);
foreach $file (#files) {
if ($file ne "." and $file ne "..") {
open FILE, "$file" or die "cannot open $file\n";
# do stuff with FILE
}
}
Note that this doesn't take care of sub directories.
I know I am way late to this discussion (ran across it while searching for grep related posts) but I am going to answer anyway:
It isn't specified clearly if these are web server logs (Apache, IIS, W3SVC, etc.) but the best tool for mining those for data is the LogParser tool from Microsoft. See logparser.com for more info.
LogParser will allow you to write SQL-like statements against the log files. It is very flexible and very fast.
Use perl from the command line, like a better grep
perl -wnl -e '/12.211.23.200/ and print;' *.log > output.txt
the benefit here is that you can chain logic far easier
perl -wnl -e '(/12.211.23.20[1-11]/ or /denied/i ) and print;' *.log
if you are feeling wacky you can also use more advanced command line options to feed perl one liner result into other perl one liners.
You really need to read "Minimal Perl: For UNIX and Linux People", awesome book on this very sort of thing.
First, use grep.
But if you don't want to, here are two small improvements you can make that I haven't seen mentioned yet:
1) Change:
#files = grep(/\.*$/,readdir(DIR));
to
#files = grep({ !-d "$dir/$_" } readdir(DIR));
This way you will exclude not just "." and ".." but also any other subdirectories that may exist in the server log directory (which the open downstream would otherwise choke on).
2) Change:
print if /12.211.23.200/;
to
print if /12\.211\.23\.200/;
"." is a regex wildcard meaning "any character". Changing it to "\." will reduce the number of false positives (unlikely to change your results in practice but it's more correct anyway).