Get file extension with multiple dots

Shell Programming and Scripting
1

I am trying to get the file extension with file names that could contain multiple dots using shell scripting. I want to find a way using the sed command.

Example Filenames:
one.dat
one.dat.002

Results:
dat

I would like to return dat in both instances using the sed command. How can I achieve this?

sed 's/^.\.//' = just returns the last three (dat and 002 respectively)
sed 's/\(.*\)\../\1/' = returns one and one.dat respectively

Any help is greatly appreciated!!!

Thanks!

2 
MYFILE="one.dat.002"
t=${MYFILE#*.}
echo "${t%%.*}"
3

Can I delete a post?

4

I am new to this type of programming so I don't know the full details. I currently have a job in Appworx (UC4 Job Scheduling) that calls a shell script (#!/bin/sh) which processes information (copying, removing files, etc). Instead of hardcoding .dat (in case later on it becomes .DAT or something else) in for the file name, I am trying to grab the extension to use it later on in my code to avoid any hard coding that may need changing later.

Below is just a sample of the code I currently have in place:

 for f in $2.DAT*
  do
    if [ -s $f ]; then
      scp -p $f $3/$2.DAT
    echo "Banner Admin job runs here"
    sleep 60

    rm $3/$2.DAT

$2 and $3 are parameters passed into the shell script.
$2's value would be one
$3's value is a target directory

Original File Names again:
one.dat
one.dat.002

5

Okay, that's what I thought. I should have left my original post there after all. :o

Anyway, given files in the current dir like this and assuming that the extension is after the first period:

$ ls
efs          one.dat      one.dat.002  one.txt      two
$

This code reads the current file list a file at a time then based on an Input Field Separator of "." parses the name into variables, which are then printed out. This should help you.

#!/bin/sh

ls|while IFS="." read filename extension the_rest
do
 echo "$filename \c"
 if [ -n "$extension" ]; then
   echo "[$extension] $the_rest"
 else
   echo "[no extension]"
 fi
done

exit 0

Output:

efs [no extension]
one [dat]
one [dat] 002
one [txt]
two [no extension]