Dir.chdir("/your/directory/here")    #changes the current working directory
getFiles=`ls *.rb`                   #passes this command to the shell
fileList=getFiles.split(/\n/)        #creates an Array separated with \n
fileList.length.times{               #opening of a block
fileName=fileList.pop                #pops the first item out of the Array
#############################
fileA=File.open(fileName,"r")        #opens the file thats in fileName as read only
doc=fileA.read                       #reads the file into the doc string
fileA.close                          #closes the file
#############################
doc.gsub!(/a/,"@")                   #replaces "a" with "@" in the doc string
#############################
fileB=File.open(fileName,"w")        #deletes and opens a the file in fileName
fileB.write(doc)                     #writes the contents of doc into the file
fileB.close                          #closes the file
#############################
}                                    #closing block
#Copyright James McCarthy 21/08/2004