If you are working with an Arduino Yún trying to npm install a package and you get the following error:

Evacuation Allocation failed - process out of memory

You can disable the memory settings for node editing the file /usr/bin/node:

$ nano /usr/bin/node

#!/bin/sh

#NODE_PATH=/usr/lib/node_modules /usr/bin/nodejs --stack_size=1024 --max_old_space_size=20 --max_new_space_size=2048 --max_executable_size=5 --gc_global --gc_interval=100 $@
NODE_PATH=/usr/lib/node_modules /usr/bin/nodejs $@

However, it might be a better idea to work locally on your computer and then move the files over the Yún. You can use something like Filezilla over SFTP. You need to install a SFTP server.

$ opkg update
$ opkg install openssh-sftp-server

Also, even better, you might not need or want to use express. If you can, try to stick to plain http module.