mass convert rar to zip (or cbr to zip) in linux

found this script on ubuntu's forums. had to modify one part of it but seems to work in linux (though you will have to input the full source directory name) I didn't look too closely at the source though.

#!/bin/bash

# Set the "field separator" to something other than spaces/newlines" so that spaces
# in the file names don't mess things up. I'm using the pipe symbol ("|") as it is very
# unlikely to appear in a file name.
IFS="|"

# The script should be invoked as "cbr2cbz {directory}", where "{directory}" is the
# top-level directory to be searched. Just to be paranoid, if no directory is specified,
# then default to the current working directory ("."). Let's put the name of the
# directory into a shell variable called WORKDIR.
# Note: "$1" = "The first command line argument"
if test -z $1; then
WORKDIR="."
else
WORKDIR="$1"
fi
echo "Working from directory $WORKDIR"

# Now, execute a loop, based on a "find" command in the specified directory. The
# "-printf "$p|" will cause the file names to be separated by the pipe symbol, rather than
# the default newline. Note the backtics ("`") (the key above the tab key on US
# keyboards).
for CBRFILE in `find $WORKDIR -name "*.cbr" -printf "%p|"`; do
# Now for the actual work. First, extract the base file name (without the extension)
# using the "basename" command. Warning: more backtics.
BASENAME=`basename $CBRFILE ".cbr"`

# And the directory path for that file, so we know where to put the finished ".cbz"
# file. You could potentially hard code this to a single directory - your choice...
# backtics again...
DIRNAME=`dirname $CBRFILE`

# For the new file name, let's convert any spaces to underscores. We'll do this with
# a "sed" (stream editor) command. Backtics again.
NEWBASEFILE=`echo "$BASENAME" | sed "s/ /_/g"`

# Now, build the "new" file name,
NEWNAME="$NEWBASEFILE.cbz"

# We need a guaranteed empty directory to work in, so I'm creating a temp
# directory under the current working directory. It will be deleted when we're
# done with it:
mkdir cbr2cbztemp
cd cbr2cbztemp

# Now that the preliminaries are done, we start doing some work.
# We need to copy the ".cbr" into the current "temp" directory for
# unpacking/repacking.
cp "$CBRFILE" .

# rename the file to a ".rar" file. I don't think this is necessary, but it shouldn't
# cause any problems...
mv "$BASENAME.cbr" "$BASENAME.rar"

# Unpack the rar file
unrar e "$BASENAME.rar"

# Delete the .rar file
rm "$BASENAME.rar"

# Create the ".cbz" file
zip "$NEWNAME" *

# And move it to the directory where we found the original ".cbr" file
cp "$NEWNAME" "$DIRNAME"

# Finally, "cd" back to the original working directory, and delete the temp directory
# created earlier.
cd ..
rm -r cbr2cbztemp

# At this point, you could potentially 'rm "$CBRFILE"' to delete the original, but
# I'd suggest not doing so until you're certain you've got a good ".cbz" file...

done

.. honestly it was driving me crazy before I found this. I assume it works for rar to zip too but no guarantees that it doesn't trash your whole system.

#!/bin/bash

# Set the "field separator" to something other than spaces/newlines" so that spaces
# in the file names don't mess things up. I'm using the pipe symbol ("|") as it is very
# unlikely to appear in a file name.
IFS="|"

# The script should be invoked as "rar2zip {directory}", where "{directory}" is the
# top-level directory to be searched. Just to be paranoid, if no directory is specified,
# then default to the current working directory ("."). Let's put the name of the
# directory into a shell variable called WORKDIR.
# Note: "$1" = "The first command line argument"
if test -z $1; then
WORKDIR="."
else
WORKDIR="$1"
fi
echo "Working from directory $WORKDIR"

# Now, execute a loop, based on a "find" command in the specified directory. The
# "-printf "$p|" will cause the file names to be separated by the pipe symbol, rather than
# the default newline. Note the backtics ("`") (the key above the tab key on US
# keyboards).
for rarFILE in `find $WORKDIR -name "*.rar" -printf "%p|"`; do
# Now for the actual work. First, extract the base file name (without the extension)
# using the "basename" command. Warning: more backtics.
BASENAME=`basename $rarFILE ".rar"`

# And the directory path for that file, so we know where to put the finished ".zip"
# file. You could potentially hard code this to a single directory - your choice...
# backtics again...
DIRNAME=`dirname $rarFILE`

# For the new file name, let's convert any spaces to underscores. We'll do this with
# a "sed" (stream editor) command. Backtics again.
NEWBASEFILE=`echo "$BASENAME" | sed "s/ /_/g"`

# Now, build the "new" file name,
NEWNAME="$NEWBASEFILE.zip"

# We need a guaranteed empty directory to work in, so I'm creating a temp
# directory under the current working directory. It will be deleted when we're
# done with it:
mkdir rar2ziptemp
cd rar2ziptemp

# Now that the preliminaries are done, we start doing some work.
# We need to copy the ".rar" into the current "temp" directory for
# unpacking/repacking.
cp "$rarFILE" .

# rename the file to a ".rar" file. I don't think this is necessary, but it shouldn't
# cause any problems...
mv "$BASENAME.rar" "$BASENAME.rar"

# Unpack the rar file
unrar e "$BASENAME.rar"

# Delete the .rar file
rm "$BASENAME.rar"

# Create the ".zip" file
zip "$NEWNAME" *

# And move it to the directory where we found the original ".rar" file
cp "$NEWNAME" "$DIRNAME"

# Finally, "cd" back to the original working directory, and delete the temp directory
# created earlier.
cd ..
rm -r rar2ziptemp

# At this point, you could potentially 'rm "$rarFILE"' to delete the original, but
# I'd suggest not doing so until you're certain you've got a good ".zip" file...

done

credit to "Lloyd B." at http://ubuntuforums.org/archive/index.php/t-522660.html.