Why doesn't this script work?

Question

I've been using this bash script:

for i in $(ls); do mv $i a$i; done

to prepend all filenames in a folder with the letter a. I'm afraid that at some point I'll accidentally use this script in the wrong directory and prepend a ton of filenames that I don't want prepended. So I decided to explicitly cite the path to the file. So now my script looks like this:

for i in $(ls /cygdrive/c/Users/path/to/Images); do mv /cygdrive/c/Users/path/to/Images/$i /cygdrive/c/Users/path/to/Images/a$i; done

It does prepend the filename with the letter a, but it also appends the filename with this  symbol.

Any ideas why it would do that?

If it helps any, I'm using cygwin on a Windows 7 box.

Thanks for the help!

Answer 1

Never parse the output of 'ls'. Do this instead:

for i in *; do mv "$i" "a${i}"; done

The reason is that file names can have characters like \r or \n in them and parsing 'ls' will NOT find them.

Update: Useful information at this link: http://mywiki.wooledge.org/ParsingLs

With the above added information from the OP, use this:

for i in /cygdrive/c/Users/path/to/Images/*; do mv "$i" "${i%/*}/a${i##*/}"; done

THIS WILL DO ONE RELATIVELY BAD THING... it will rename ALL files, every time you run it. This means file 'foo' will be 'afoo'. When you run it again, it will be 'aafoo' then 'aaafoo', etc. You can program around this by avoiding any files that start with 'a' but that will avoid ALL files starting with 'a' even if they have not yet been renamed in the script.

Answer 2

test for correct directory, or move to correct directory (or both):

from here

E_WRONG_DIRECTORY=73

TargetDirectory=/cygdrive/c/Users/path/to/Images

cd $TargetDirectory
echo "Changing names in $TargetDirectory."

if [ "$PWD" != "$TargetDirectory" ]
then    # Keep from wiping out wrong directory by accident.
  echo "Wrong directory!"
  echo "In $PWD, rather than $TargetDirectory!"
  echo "Bailing out!"
  exit $E_WRONG_DIRECTORY
fi  

Answer 3

Please declare ls /cygdrive/c/Users/path/to/Images as a variable. Please use variable as ${i} instead of $i. also Use, " " for path's .