How to split a file into smaller files

Shell Programming and Scripting
1

Hi,
I have a big text file with m columns and n rows. The format is like:

STF123450001000200030004STF123450005000600070008STF123450009001000110012
STF234560345002208330154STF234590705620600070080STF234567804094562357688
STF356780001000200030004STF356780005000600070080STF356780800094562657687
....
....
....
....

What I want is read the file, split the first line, write the first STF section to file1 and second STF section to file 2 and so on; then read the second line, append the first STF section to file1 as the second line and second STF section to file2 as the second line and so on....

Thanks!

2 
cut -c1-24 infile > out1
cut -c25-48 infile > out2
cut -c49- infile > out3
3

Or if the actual data's wider, this uses "STF" as its field separator and prints different field numbers to different filenames:

awk -v FS="STF" '{ for(N=2; N<=NF; N++) print FS $N >"file"N }'

to make file1, file2, ...