使用php，grep和regex来搜索和替换文件中的代码行

Question

I have a php file that can read the contents of other files perfectly and return them as a string.

$contents = $file->read(); // return as string.

i need to be able to search and replace certain lines

lines that begin with $this->Session->setFlash and end with , true)); must be replaced with

lines that begin with $this->Session->setFlash and end with , true), 'default', array('class'=>'flash_failure'));

I have grep in my machine, if that helps.

finally after the contents is changed, i have a function that will write the contents back

$file->write($contents);

I know this helps to find the lines, but I have no idea how to replace.

^.*Session->setFlash.*, true\)\);$

Answer 1

the solution is thus:

$contents = preg_replace('/^(.*Session->setFlash.*, true\))\);$/m',
                                         "$1, 'default', array('class'=>'flash_failure'));", $contents);

the multiline modifier is key.