Saturday, November 14, 2009

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

Friday, November 13, 2009

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