Currently, my Perl output is hard-coded to dump into the following Unix directory:
my $stat_dir = "/home/courses/" . **NEED DIR VAR HERE**;
The filename is built as such:
$stat_file = $stat_dir . "/" . $sess.substr($yr, 2, 2) . "_COURSES.csv";
I need a similar approach to building Unix directories, but I need to check if they exist first before creating them.
How can I do auto-numbering (revisions) of the $stat_file so that when these files get pumped into the same directory, they do not overwrite or append to existing files in the directory?
Erm... mkdir $stat_dir unless -d $stat_dir?
It really doesn't seem like a good idea to embed 'extra' questions like that.
Use the -d operator and File::Path.
use File::Path qw(make_path);
eval { make_path($dir) };
if ($#) {
print "Couldn't create $dir: $#";
}
make_path has an advantage over mkdir in that it can create trees of arbitrary depth.
And use -e to check file exists
my $fileSuffix = 0;
while (-e $filename) {
$filename = $filePrefix . ++$fileSuffix . $fileExtension;
}
Remember the directory's -d existence doesn't mean -w writable. But assuming you're in a personal area the mkdir($dir) unless(-d $dir) would work fine.
Perl has a built-in function mkdir
Take a look at perldoc perlfunc or the mkdir program from Perl Power Tools.
I believe it is safe to create a directory that already exists, take a look at the docs.
Related
I have a script like this to list every FILES inside my root path
use strict;
use File::Find qw(find);
my $path = "<my root path>";
find(\&Search, $path);
sub Search{
my $filename = $File::Find::name;
if(-f $filename){
print $filename."\n";
}
}
My point is to try to list all the FILES. However, it also listed the symlink inside my $root. I modify my Search function like this and it worked:
sub Search{
my $filename = $File::Find::name;
#Check if $filename is not symlink first
if(!-l $filename){
if(-f $filename){
print $filename."\n";
}
}
}
But it seem awkward right ? Why do we need two if condition just to verify $filename is the real file and not a symlink !!!
Is there anyone can suggest a better, more decent solution for this ?
Thank you and best regards.
Alex
-f is testing for file, and that includes symlinks. So yes, you do have to test both.
One slightly useful thing, is that you can probably just do:
if ( -f and not -l ) {
because File::Find sets $_ to the current file, and the file tests default to using that too. (won't work if you turn on no_chdir though).
You may also want to consider File::Find::Rule as an alternative to File::Find.
stat and lstat are identical except when it comes to symlinks. The former collects information about the linked file, whereas the latter collects information about the link itself.
The -X EXPR uses stat. lstat is needed here.
sub Search {
my $filename = $File::Find::name;
if (!lstat($filename)) {
warn("Can't stat $filename: $!\n");
return;
}
say $filename if -f _;
}
Bonus: Error checking becomes much simpler when you pre-call stat or lstat.
I usually get a bunch of files whose name start with a dash '-' . This is causing all sorts of problem when i do any kind of linux commands because anything after - is interpreted as a flag.
What is the fastest way to rename these files without dash character in the front of the file. I can manually rename each file by adding a '--' in front of the file name.For eg: '-File1' will be renamed as
mv -- -File1 File1
But this is not ideal when i have to rename 100's of files on the fly. Currently I have to export it out and use a windows program so I can batch rename them and then upload it back to a Linux box.
The easiest way to refer to such a file is ./-File1. (You only have the problem if the file is in the current directory, anyway.) Maybe if you get used to that it's not so bad.
To bulk rename them, you could do something like:
for f in -*; do mv "./$f" "renamed$f"; done
or, as #shellter suggests in a comment, to reproduce the example in the OP:
for f in -*; do mv "./$f" "${f#-}"; done
Note: the above will only remove a single - from the name.
If you have the util-linux package (most do?):
rename - '' ./-*
man rename
Might be easier to do this in the shell, but if you're worried about special cases or if you would just rather use perl there's a couple ways to do it. One is to use File::Copy mv:
use strict;
use warnings;
use File::Copy qw(mv);
opendir(my $dir, ".") or die "Can't open $!";
foreach my $file (readdir($dir)) {
my $new_name = $file =~ s/^-+//r; #works if filename begins with multiple '-'s
if ($new_name ne $file) {
say "$file -> $new_name";
mv $file, $new_name;
}
}
or use the rename builtin, but this theoretically can not work for some system implementations:
rename $file, $new_name; #instead of mv $file, $new_name;
In either case, if a file with the new name exists it will get silently overwritten with this code. You might need some logic to take care of that:
# Stick inside the "if" clause above
if (-e $new_name) {
say "$new_name already exists!"
next;
}
Using find:
find -name '-*' -exec rename -- - '' {} \;
hi i have written a perl script which copies all the entire directory structure from source to destination and then i had to create a restore script from the perl script which will undo what the perl script has done that is create a script(shell) which can use bash features to restore the contents from destination back to source i m struggling to find the correct function or command which can copy recursively (not an requirement) but i want exactly the same structure as it was before
Below is the way i m trying to create a file called restore to do the restoration process
i m particularly looking for algorithm.
Also restore will restore the structure to a command line directory input if it is supplied if not You can assume the default input supplied to perl script
$source
$target
in this case we would wanna copy from target to source
So we have two different parts in one script.
1 which will copy from source to destination.
2 it will create a script file which will undo what part 1 has done
i hope this makes it very clear
unless(open FILE, '>'."$source/$file")
{
# Die with error message
# if we can't open it.
die "\nUnable to create $file\n";
}
# Write some text to the file.
print FILE "#!/bin/sh\n";
print FILE "$1=$target;\n";
print FILE "cp -r \n";
# close the file.
close FILE;
# here we change the permissions of the file
chmod 0755, "$source/$file";
The last problem i have is i couldn't get $1 in my restore file as it refers to a some variable in perl
but i need this for getting command line input when i run restore as $0 = ./restore $1=/home/xubuntu/User
First off, the standard way in Perl for doing this:
unless(open FILE, '>'."$source/$file") {
die "\nUnable to create $file\n";
}
is to use the or statement:
open my $file_fh, ">", "$source/$file"
or die "Unable to create "$file"";
It's just easier to understand.
A more modern way would be use autodie; which will handle all IO problems when opening or writing to files.
use strict;
use warnings;
use autodie;
open my $file_fh, '>', "$source/$file";
You should look at the Perl Modules File::Find, File::Basename, and File::Copy for copying files and directories:
use File::Find;
use File::Basename;
my #file_list;
find ( sub {
return unless -f;
push #file_list, $File::Find::name;
},
$directory );
Now, #file_list will contain all the files in $directory.
for my $file ( #file_list ) {
my $directory = dirname $file;
mkdir $directory unless -d $directory;
copy $file, ...;
}
Note that autodie will also terminate your program if the mkdir or copy commands fail.
I didn't fill in the copy command because where you want to copy and how may differ. Also you might prefer use File::Copy qw(cp); and then use cp instead of copy in your program. The copy command will create a file with default permissions while the cp command will copy the permissions.
You didn't explain why you wanted a bash shell command. I suspect you wanted to use it for the directory copy, but you can do that in Perl anyway. If you still need to create a shell script, the easiest way is via the :
print {$file_fh} << END_OF_SHELL_SCRIPT;
Your shell script goes here
and it can contain as many lines as you need.
Since there are no quotes around `END_OF_SHELL_SCRIPT`,
Perl variables will be interpolated
This is the last line. The END_OF_SHELL_SCRIPT marks the end
END_OF_SHELL_SCRIPT
close $file_fh;
See Here-docs in Perldoc.
First, I see that you want to make a copy-script - because if you only need to copy files, you can use:
system("cp -r /sourcepath /targetpath");
Second, if you need to copy subfolders, you can use -r switch, can't you?
I'm very new to Perl, and I would like to make a program that creates a directory and moves a file into that directory using the Unix command like:
mkdir test
Which I know would make a directory called "test". From there I would like to give more options like:
mv *.jpg test
That would move all .jpg files into my new directory.
So far I have this:
#!/usr/bin/perl
print "Folder Name:";
$fileName = <STDIN>;
chomp($fileType);
$result=`mkdir $fileName`;
print"Your folder was created \n";
Can anyone help me out with this?
Try doing this :
#!/usr/bin/perl
use strict; use warnings;
print "Folder Name:";
$dirName = <STDIN>;
chomp($dirName);
mkdir($dirName) && print "Your folder was created \n";
rename $_, "$dirName/$_" for <*.jpg>;
You will have a better control when using built-in perl functions than using Unix commands. That's the point of my snippet.
Most (if not all) Unix commands have a corresponding version as a function
e.g
mkdir - see here
mv - See here
Etc. either get a print out of the various manual pages (or probably have a trip down to the book shop - O'Reilly nut shell book is quite good along with others).
In perl you can use bash commands in backticks. However, what happens when the directory isn't created by the mkdir command? Your program doesn't get notified of this and continues on its merry way thinking that everything is fine.
You should use built in command in perl that do the same thing.
http://perldoc.perl.org/functions/mkdir.html
http://perldoc.perl.org/functions/rename.html
It is much easier to trap errors with those functions and fail gracefully. In addition, they run faster because you don't have to fork a new process for each command you run.
Perl has some functions similar to those of the shell. You can just use
mkdir $filename;
You can use backquotes to run a shell command, but it is only usefull if the command returns anything to its standard output, which mkdir does not. For commands without output, use system:
0 == system "mv *.jpg $folder" or die "Cannot move: $?";
How do I run a Perl script on multiple input files with the same extension?
perl scriptname.pl file.aspx
I'm looking to have it run for all aspx files in the current directory
Thanks!
In your Perl file,
my #files = <*.aspx>;
for $file (#files) {
# do something.
}
The <*.aspx> is called a glob.
you can pass those files to perl with wildcard
in your script
foreach (#ARGV){
print "file: $_\n";
# open your file here...
#..do something
# close your file
}
on command line
$ perl myscript.pl *.aspx
You can use glob explicitly, to use shell parameters without depending to much on the shell behaviour.
for my $file ( map {glob($_)} #ARGV ) {
print $file, "\n";
};
You may need to control the possibility of a filename duplicate with more than one parameter expanded.
For a simple one-liner with -n or -p, you want
perl -i~ -pe 's/foo/bar/' *.aspx
The -i~ says to modify each target file in place, and leave the original as a backup with an ~ suffix added to the file name. (Omit the suffix to not leave a backup. But if you are still learning or experimenting, that's a bad idea; removing the backups when you're done is a much smaller hassle than restoring the originals from a backup if you mess something up.)
If your Perl code is too complex for a one-liner (or just useful enough to be reusable) obviously replace -e '# your code here' with scriptname.pl ... though then maybe refactor scriptname.pl so that it accepts a list of file name arguments, and simply use scriptname.pl *.aspx to run it on all *.aspx files in the current directory.
If you need to recurse a directory structure and find all files with a particular naming pattern, the find utility is useful.
find . -name '*.aspx' -exec perl -pi~ -e 's/foo/bar/' {} +
If your find does not support -exec ... + try with -exec ... \; though it will be slower and launch more processes (one per file you find instead of as few as possible to process all the files).
To only scan some directories, replace . (which names the current directory) with a space-separated list of the directories to examine, or even use find to find the directories themselves (and then perhaps explore -execdir for doing something in each directory that find selects with your complex, intricate, business-critical, maybe secret list of find option predicates).
Maybe also explore find2perl to do this directory recursion natively in Perl.
If you are on Linux machine, you could try something like this.
for i in `ls /tmp/*.aspx`; do perl scriptname.pl $i; done
For example to handle perl scriptname.pl *.aspx *.asp
In linux: The shell expands wildcards, so the perl can simply be
for (#ARGV) {
operation($_); # do something with each file
}
Windows doesn't expand wildcards so expand the wildcards in each argument in perl as follows. The for loop then processes each file in the same way as above
for (map {glob} #ARGV) {
operation($_); # do something with each file
}
For example, this will print the expanded list under Windows
print "$_\n" for(map {glob} #ARGV);
You can also pass the path where you have your aspx files and read them one by one.
#!/usr/bin/perl -w
use strict;
my $path = shift;
my #files = split/\n/, `ls *.aspx`;
foreach my $file (#files) {
do something...
}