Join and Split Files (Including Video) in Linux [Howto]

Update: There is also a Java version and a Windows one, see the update at the bottom of the post for a link.

1. How to join files under Linux

Let's say you downloaded some videos of Youtube which all are a part of a larger video that was splitted into parts. A good idea would be to join those video files into one big file. Here's how to do that in Linux:

cat file.avi.* > file.avi

(presuming your files are named file.avi.001, file.avi.002 and so on)

That can be done on any file type but if it's a video file we're not done yet, the new file.avi only shows the first video and the sound might be broken. Now we need to fix it. First, install mencoder and mplayer:

sudo apt-get install mencoder mplayer

and then run this command on your new video file.avi:

mencoder -forceidx -oac copy -ovc copy file.avi -o file_final.avi

Now we are done and you can play the file.

2. How to split a file into multiple smaller files under Linux

To split a file, you need to install lxsplit. Download it from here (there are source files, .rpm and .deb files) and install it.
Then, to split files, run this command:

lxsplit -s file.avi 50M

and replace file.avi with your big file and 50M with the size you want the splitted files to have.

lxsplit can also be used to join multiple files:

lxsplit -j file.avi.001

That will join all files that begin with "file.avi" into a one big "file.avi" file. Please note that again, you need to run the mencoder command I told you about at point 1 for the video to run correctly.

There is also a full graphical user-interface for Gnome and KDE for this lxsplit but there are only source files. If you want you can download it from here. To be able to run it, you will also need Kylix Linux libraries which you can get from here.

Update: there is also a Java version which runs on any operating system and about two windows versions: one with GUI and one command line tool. Read about it here.