To split a large file into smaller ones:
Lets say you have to send your personal video file of size 100MB to your friend through Gmail but gmail has a maximum file upload limit of size 20MB.So you have to split it into 5 smaller files of size 20MB and upload it.For this you have to go to the directory where the file is stored and use the following command in the terminal:
$ split –b20m Largefilename Smallfilename
where 20m is the size of output file in MB,to split in KB put k instead of m.various other options are also available to split command,to know them just type
$ split --help
To join smaller files into a larger one:
These days most files hosted at major file hosting sites are split into smaller files such as *.001…009 or *.part01…*.part09 etc.To join these files you don’t have to search for any external softwares,you just have the commands built into every GNU/Linux system.
To join the part files open up the terminal and navigate to the directory where the files are placed and execute the command:
$ cat partfilename* > outputfilename
For example if the file names are
video.avi.01
video.avi.02
video.avi.03 etc.use
$ cat video.avi.* > video1.avi
Ref:
http://blulin.wordpress.com/2009/02/07/split-and-join-large-files-in-gnulinux-just-using-terminal/