This will backup all tables starting with "prefix_" to a gzipped file backup.sql.gz.

echo "SHOW TABLES" | mysql -uUSERNAME -pPASSWORD -D DBNAME | grep ^prefix_ | xargs mysqldump -uUSERNAME -pPASSWORD DBNAME | gzip -c > backup.sql.gz

You have to replace USERNAME, PASSWORD and DBNAME twice.

Note: On textdrive you want to add --skip-opt to mysqldump, otherwise the command will abort with an error because privs for lockings tables are missing (for me at least).

To check which tables were backed up, you can use:

zcat test.sql.gz | grep CREATE

Read http://dev.mysql.com/doc/mysql/en/mysqldump.html to find out which other options to add to mysqldump

This shell snippet counts all lines in all .php files (in and beneath the current path ".") that are non-blank and not comments (yes, it also discards multiline comments).

find . -name '*.php' | xargs cat | sed -re ':top /\/\*.*\*\// { s/\/\*.*\*\///g ; t top }; /\/\*/ { N ; b top }' | awk '$0 !~ /^[\t[:space:]]*($|(\/\/)|(#))/' | wc -l

This will upload all files in the current directory ending in jpg jpeg or gif through your textpattern-admin panel to your site.

Save this as a shell script, adjust the first 3 variables and excute. (Note: LOGIN and PASS should be ascii only, or else manually url-encoded)

URL='http://www.mysite.com/textpattern/'
LOGIN='simplename'
PASS='yourpassword'

COOKIE=$(curl -s -D - -d "p_userid=$LOGIN&p_password=$PASS" \
    $URL | head -n10 | sed -n 's/^Set\-Cookie\: //p')

if [ -z $COOKIE ] 
then 
  echo "Can't log in."
  exit 1
else 
  echo "Cookie: "$COOKIE
fi


for file in $(ls -1|egrep '(gif)|(jpe?g)$') ; 
do
 echo "Sending "$file
 curl -s -H "Cookie: $COOKIE" -F "thefile=@$file" \
   -F "event=image" -F "step=image_insert" $URL > /dev/null
done

This will not output anything. But after it returns to the prompt, log in to textpattern and take a look into the image section.

Update: Added rudimentary check wether login is successful and basic progress meter.