Monthly Archives: April 2013

Alexander Brevig : The //* /*/ //*/ comment toggle trick

Just saw this on HN. Alexander Brevig : The //* /*/ //*/ comment toggle trick.

I’ve been using something very similar – the only difference between the last comment //*/ vs /**/

//*
someFunction();
/*/
someOtherFunction();
/**/

This technique is surprisingly “portable” – works in C++, Javascript, PHP, amongst others. And it works better than if (0) { someFunction(); } else { someOtherFunction(); } ‘cos syntax-highlighting works.

Another trick that I’ve used by abusing comments is to produce output that are both valid Javascript as well as HTML – at least to most browsers:

//<!--
alert("hello");
//-->
//<html><body>some text</body></html>

In Javascript context it’ll show a “hello” prompt, whereas in HTML context it’ll show “// //some text”. This can be used when say you’re returning a Javascript API and someone is misinterpreting it as HTML. You can of course be creative about the “some text” part. 🙂

Setting up a proper Linux environment on Synology DS412+

We recently got a Synology DS412+ as an office NAS. First thing to do is to set up a proper Linux environment on the device.

Gaining root on Synology NAS is easy – just log in as root with the same password as admin. However, most (all?) commands are mapped to BusyBox, which provides watered-down version of many *nix commands. Good thing is there’s an active modding community and it’s also sanctioned by Synology. A good place to start is here.

First install the bootstrap

cd /tmp
wget http://ipkg.nslu2-linux.org/feeds/optware/syno-i686/cross/unstable/syno-i686-bootstrap_1.2-7_i686.xsh
chmod u+x syno-i686-bootstrap_1.2-7_i686.xsh
./syno-i686-bootstrap_1.2-7_i686.xsh

Then install optware-devel, which installs many of the common *nix tools and binaries for building programs from tar source.

/opt/bin/ipkg install optware-devel

Unfortunately, installation fails halfway ‘cos wget-ssl which is included in optware-devel conflicts with the wget installed.

# ipkg install -verbose_wget wget-ssl
Installing wget-ssl (1.12-2) to root...
Nothing to be done
An error ocurred, return value: 1.
Collected errors:
ERROR: The following packages conflict with wget-ssl:
         wget

Someone posted a solution here and here, but both are for arm-based devices. Digging further, I found the source of the i686 packages here and with that the problem is resolved.

cd /tmp
wget 'http://ipkg.nslu2-linux.org/feeds/optware/syno-i686/cross/unstable/libidn_1.25-1_i686.ipk'
wget 'http://ipkg.nslu2-linux.org/feeds/optware/syno-i686/cross/unstable/wget-ssl_1.12-2_i686.ipk'
ipkg remove wget
ipkg install libidn_1.25-1_i686.ipk
ipkg install wget-ssl_1.12-2_i686.ipk

export PATH=/opt/bin:$PATH
ipkg update
ipkg install optware-devel

The export step is important, ‘cos it will make ipkg use the new wget.

A few other things to finish up,

  • ipkg install util-linux
  • install bash, vim, screen
  • change default root shell to /opt/bin/bash,
  • add /opt/bin to PATH in .profile,
  • set PS1=’\h:\w\$ ‘