Unix - tips, scripts, tricks, etc

1. Create a 1GB file:
/usr/sbin/lmktemp filename1 10737418424
2. Create a second 1GB file:
cp filename1 filename2
3. To create a 2GB file, append the first file to the second file:
cat filename1 >> filename2
4. To create a 3GB file, append the first file to the second file again:
cat filename1 >> filename2