UNIX for Dummies Questions & Answers

Okay so here's something that's confusing me: I have a script that's designed to remove the words "new_" from the front of any file except two exceptions and it looks something like this...

Code:

for i in new_*
do
   if [[ `echo $i` != new_dat.bak ]] && [[ `echo $i | cut -c1-7` != new_ig_ ]]; then
          j=`echo "$i"|cut -c5-`
          mv $i $j
    fi
done

But what's happening is that it works perfectly on any directory except one that has no files starting with "new_". In that case it will still get in the if statement and report a single occurrence. It will report that it found a file called "new_*"

This I do not understand. Can someone please explain why it is seeing a non-existent file that just happens to match the description given in the for loop? Thanks.

When there are new_* files in a directory, * wildcard is being expanded and so file names are being passed in for loop as value of i.
When there is no file of type new_*, * wildcard is not expanded and so new_* is passed as it is in the for loop.
All is that, this for loop will execute atlest once, either for actual files ( if present) or for new_*

Ah. Thanks for the clarification. I conceived a work around was to add a if test -f argument inside the loop to make sure it is a real file before trying to move it but I'd prefer to avoid the situation entirely. Is that possible?

---------- Post updated at 06:36 PM ---------- Previous update was at 06:34 PM ----------

Thanks for cleaning up my post Scott. Sorry it was a little sloppy.

Code:

$ ls
new_a		new_b		new_c		new_dat.bak	new_ig_1	new_ig_2

Code:

ls new_* | while read FILE; do
  [[ "$FILE" = new_dat.bak ]] || [[ "$FILE" = new_ig* ]] && continue
  mv "$FILE" "${FILE#new_*}"
done

Code:

$ ls
a		b		c		new_dat.bak	new_ig_1	new_ig_2

Code:

#!/bin/ksh
exec 2>/dev/null
ls new_* | while read i
do
    if [[ `echo $i` != new_dat.bak ]] && [[ `echo $i | cut -c1-7` != new_ig_ ]]; then
          j=`echo "$i"|cut -c5-`
          mv $i $j
    fi
done

Excellent alternatives. Thank you both