Change mysql_ to mysqli_ functions

In the process of upgrading PHP5.3 code I had to change all deprecated mysql_* functions to their mysqli_* counterparts.

For a lot of functions the signature stayed the same.

But mysqli_query and mysqli_connect have differences. So you can’t just find and replace them.

Instead of doing this manually, I wanted to find and replace recursively while changing the order of the arguments.

In vim:

# change mysql_query(param1, param2) to: 
# mysqli_query(param2, param1)
:%s/mysql_query(\(.\{-}\),\(.\{-}\))/mysqli_query(\2, \1)/g

Using sed:

# on linux

# mysql_query(param1, param2) to 
# mysqli_query(param2, param1)
sed -i 's|mysql_query(\(.*\),\(.*\))|mysqli_query(\2, \1)|g' devices.php

# on mac (otherwise you get the 'invalid command mode' when 
# you run the sed command)

# mysql_query(param1, param2) to: 
# mysqli_query(param2, param1)
sed -i '' -e 's|mysql_query(\([^,]*\),\([^)]*\))|mysqli_query(\2, \1)|g' devices.php

Recursively changing all files:

# in all files under current directory:
# mysql_query(param1, param2) to: 
# mysqli_query(param2, param1)
fgrep -rl mysql_query . | while read file; do
  sed -i '' -e 's|mysql_query(\([^,]*\),\([^)]*\))|mysqli_query(\2, \1)|g' $file
done

Note that sed cannot do non greedy matching.

That’s why we’re searching for anything but the separator until the separator like this:

# non greedy matching with sed
\([^,]*\),

It basically states: get everything except for the comma until you get a comma (which is the first one to appear).