bash - Execute command on all files in a directory

Question

Could somebody please provide the code to do the following: Assume there is a directory of files, all of which need to be run through a program. The program outputs the results to standard out. I need a script that will go into a directory, execute the command on each file, and concat the output into one big output file.

For instance, to run the command on 1 file:

$ cmd [option] [filename] > results.out

Answer 1

The following bash code will pass $file to command where $file will represent every file in /dir

for file in /dir/*
do
  cmd [option] "$file" >> results.out
done

Example

el@defiant ~/foo $ touch foo.txt bar.txt baz.txt
el@defiant ~/foo $ for i in *.txt; do echo "hello $i"; done
hello bar.txt
hello baz.txt
hello foo.txt