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Copy and change zip archive

I have a zip archive with a lot of files(other zip files, text files, gz archives) inside it. Need to create a new zip file with the same structure. Some info in the new zip must be changed. For example, need to change all 'a' letters in all files to the letter 'b'. Need to resolve the task without creating temp files or unpacking archives to the temp folders. How can I do it?

If you need to do this entirely streaming, you will need to parse the zip file format, copy entries that are not being modified to a new zip file, and process entries that are being modified by decompressing them and recompressing them in streams, copying to the new zip file.
If you don't need to do this streaming, then extract the entries you want to modify, removing them from the zip file. Modify them. Then add them to the zip file using any zip utility.

Read only file in Zip archive

I'm trying to generate a zip file with java.util.zip API and I haven't found any way to set zip entry as read only file. I would like to create a new ZIP archive, put files inside it and set read only flag for all those files that appear inside of the ZIP file (on Windows platform).
I am aware that java.util.zip API works with Streams instead of File objects (File object has method setReadonly()).
I also tried with Apache Commons Compress API and haven't found solution as well.
Please help!

How to combine multiple .gz files in Java?

gz files in one directory. I want to combine them in one big .gz file and unzip it and load it into HDFS.
For e.g. repo contains files a.gz,b.gz,c.gz. Now I want to combine them into one file called d.gz I want to unzip it and load into HDFS. These .gz files are CSV files.
To unzip it I know I can GZIPInput/OutputStream but how do I combine files into one big files in Java.
Please guide. Thanks in advance.

A gz file contains exactly one file. It's not meant to contain multiple files.
The best way to do this is TAR the files together then GZ the resulting TAR. TAR has command line options to automate this into a single operation. For Java, use jtar: https://code.google.com/p/jtar/
Alternatively, a ZIP file may be what you're looking for.

How can I add a directory (tree of files) into a zip?

How can I add/modify/delete/merge recursive directory in a zip file (in Java) without file system?
Do I have to respect the order of zip entries?
Yes, I know merging directories is very complex job..

If you need to add whole directory with files to zip archive recursively only by Java core efforts, then you can use good example from Mkyong's blog. If you need to append files to existing zip-file, the you should use a link from #McDowell's comment: Appending files to a zip file with Java

There is no simple answer, your going to need to write a faire bit of code. You can't use the JDK ZipFile class, as that only supports reading zip files.
Instead use Commons Compress. Have a look at the examples and the zip documentation to get going.
Basically you'll need to open an input zip file, and an output zip file. Read each entry in tern, and decide whether to write it to the output, transform and write, add a new entry, or skip it, . When you get to the end close both zip files.
When processing a zip file, it's not really recursive, as all the entries are just a linear list with a path and filename. The recursive part comes when a zip contains a zip, and that is quite easy to handle.

Copy a file or multiple files form a zip file without actually unzipping it using perl or java

I have a couple of zip file which have multiple files and folders. It basically contains text files. Say extension 'a' and 'b'.
I want to separate the extension 'a' files and extension 'b' files into separate zip files, using a perl script or java code.
Instead of unzipping the files, can I just pick the contents and put it into another zip file. Is this even possible? Any help would be great.
The reason why I was wondering this is I have large number of zip files of large size, so if this is possible my code will be very efficient.
And any comments whether to use perl or java would be a bonus.
Thank you.

You can use the Java ZipFile class to read contents of a zip file, iterate over the entries in the zip and obtaining input streams for relevant entries. Using the ZipOutputStream it is possible to directly put the files into a new zip file - although they are decompressed/compressed in between. I don't know of a tool that can copy the zipped contents directly.

This might be done uzing Perl Archive::Zip library:
Actual oneliner might looks like the following:
perl -MArchive::Zip -e 'Archive::Zip->new("test.zip")->extractMember("testx.txt", "foo.txt");'
But I would like to provide full code with even some checks:
use Archive::Zip;
my $zip = Archive::Zip->new("test.zip");
my $file_path = "test.txt";
my $PARANOID = 1;
if ($PARANOID) {
my $file = $zip->memberNamed($file_path);
unless ($file) {
die "File '$file_path' not found in the archive";
}
}
$zip->extractMember($file_path, "extracted_file.txt");
Please note that you need to have Archive::Zip library installed:
cpan Archive::Zip
Or, if you are more confident with Perl ecosystem and have shiny cpanm utility installed:
cpanm Archive::Zip

I just found that zip on Unix has a --copy option which copies a file from one archive to another. I don't believe it decompresses the file in the process so it should be just what you (and I) need.
Syntax is:
$ zip source.zip "*.c" --copy --out destination.zip