Thank you very much for who can solve this bash script:
"Create a bash procedure createdata that creates collections (directories) that that will have to contain a random number, comprised between 300 and 600, of binary files of dimension comprised between 10 Kbytes and 30 kbytes.
Also the names of the files are random and are composed from 20 chars plus the jpg extension."
createdata /data 20 result: /data tlc01 collection001 ttretdgdfgasjojgvao.jpg grtghgfhysystudbbnh.jpg ... ... collection019 ...
it must create therefore beyond to the directory given (data) the subdirectory tlc01, then the 20 collections (subdirectories of tlc01)
Sorry for my english, hope you understand..
Thanks indeed for who can help me :-)