create file for a desired file size.

Hello all.

This is my first post here.
I'm not an unix guy so please bear with me. At work, from time to time I get the need to have some 'junk' files of varying sizes. Typically, I write a small 'script' which cats a file to another file. I run this manually until it reaches closer to a desired size.

My question: Is there a better way to create a file which comes to the exact size as specified. Please give me pointers. I have to write this in Aix environment. Thanks a lot in advance!

q1: what's a junk file ?
q2: 4 what you need a junk file ?
q3: did you try: man mkfile ?

Yes and no. What you are doing is fairly common for pure
shell script programming. A more efficient way is to write
a small C program to create a file of the exact size that
you want i.e.

mkemptyfile <filename> <size>

Another way is to use /dev/zero in conjunction with the dd utility i..e.

dd if=/dev/zero of=filename bs=1024 count=20

creates the zeroized file "filename" of size 20K.