UNIX for Dummies Questions & Answers

So seems only way I'm going to learn is by asking. In the following and I can tell you that $ENV=384:

Code:

grep $ENV $TSH/ftp/some.files | while read ELABEL EENV EFILE RFILE
  do
    if [[ -n $RFILE ]]; then
      rm -ef ${RFILE}*
    else
      rm -ef ${EFILE}*
    fi
  done

In the some.files :

Code:

bgtest /usr/384 BL.X1
bgtest /usr/384 BL.X2
bgtest /usr/384 BL.X3
bgtest /usr/384 BL.X4
bgtest /usr/384 BL.X5
bgtest /usr/383 BL.X6
bgtest /usr/383 BL.X7

Once again, I know basic scripting if you can call it that
Whats really throwing me off here is the variables in {}
What is that piece of code trying to do exactly? Well, from the info I've given.

This is a different piece I've noticed that leads back to the {}. I'll see a file name, say:
BKFILE=$FTPDIR/$TDG/${ZFILE}.out
And I'll know the value of $FTPDIR and $TDG, but where is it getting the value for ${ZFILE} when it hasnt been defined previously in the script.

Using braces like that just seperates the variable name from the rest of the line.
eg

Code:

THING="some"
echo ${THING}otherthing

Produces "someotherthing"

But

Code:

THING="some"
echo $THINGotherthing

Would print nothing as there is no variable called 'THINGotherthing'

In the code you've listed, it looks like it's grep'ing out all the lines containing '384' (or whatever $ENV is set to), then splitting each line into different variables.
In your example:
ELABEL gets 'bgtest'
EENV gets '/usr/384'
EFILE gets 'BL.X1' (or BL.X2 ... a different one each time through the loop)
RFILE gets nothing but if there was an extra word on teh end of any of those lines' it would go into RFILE.

If RFILE exists, it looks for any files starting with that name and deletes them.
If RFILE doesn't exist, it deletes any files starting with EFILE (BL.X1 etc).

Thanks for your explanation, really cleared it up.