Linux – Break file into smaller files. Put file back together again.

If for instance you were wanting to break a large file down so that it can be written to a CD you can use the split command with the -bytes flag.

split [option] [input] [output]

For example you wish to break a 10G file into 10 files of 1G size:

$ split -bytes=1G /path/to/large/file /path/to/output/file/prefix

or

$ split -b1G /path/to/large/file /path/to/output/file/prefix

To put the file back together you need to cat the files back together:

$ cat prefix* > newfilename

Further Reading

http://linux.about.com/library/cmd/blcmdl1_split.htm
http://linux.die.net/man/1/split