Shell Programming and Scripting

abc.* , 
xyz*, 
djj*, 
iwe*, 
weewe*, 
rier*, 
3948903ddfgf*

#!/bin/bash

cd /output

for f in abc. xyz djj iwe weewe rier 3948903ddfgf; do

# ensure that we pick up a non-blank string 
# (not likely to happen, but if it does we will end up doing rm *)
# this will NOT work if the filenames have newlines in them

  if [ "x$f" != "x" ]
  then
     last=`ls -tr ${f}* |tail -1`
     save="save_$last"
     mv $last $save
     rm ${f}*
     mv $save $last
  fi

done

$ ruby -e '["abc.","xyz","djj""].each{|c| Dir["#{c}*"].sort{|x,y| File.mtime(x)<=>File.mtime(y)}[0..-2].each{|f| File.unlink(f)} } '

ls -ct *.txt | awk '
BEGIN{ flag=1; }
{
if (flag){
# keep the latest file
flag=0;
} else {
# Remove the old files
print "rm "$1;
}
}
'| sh