Creating specific sized file

To create a specific sized file, dd command can be used. Example below will create a file named output with 10M size:

$ dd if=/dev/zero of=output bs=1M count=10

where bs is block size, and count is number of blocks to be created

The output:

$ ls -lh output

-rw-r--r-- 1 user user 10M 2009-11-14 06:21 output

Splitting big files

To split big files, split command can be used. Below is command used to split 400MB file named bigfile into 100MB chunk files named smallfile0*

$ split -b 100M -d --verbose bigfile smallfile

creating file 'smallfile00'

creating file 'smallfile01'

creating file 'smallfile02'

creating file 'smallfile03'

where -b is for byte size, -d is for numeric suffixes and smallfile is the prefix to be used

The output is:

$ ls

bigfile smallfile00 smallfile01 smallfile02 smallfile03

To recover back the splitted files into a file named newbigfile:

$ cat smallfile0* > newbigfile