There are other shells which have a completely different syntax and other scripting languages such as Perl and PHP so when writing a shell script you can indicate the correct interpreter using the ‘hash bang bin bash’ comment to indicate you are using bash. I.e.

#!/bin/bash

Some lazy programmers don’t indicate the exact shell they require and use

#!/bin/sh

to mean bash when it means sh.

Ubuntu, in their wisdom, have decided to go for dash as their shell. It is an evolution of the Almquist shell and is smaller and lighter weight than bash however they install bash anyway. dash and bash have the common subset of sh commands but are different. So if you find you have a problem building or similar on Ubuntu it may be that the wrong shell is being used. Ubuntu has a symlink as follows:

lrwxrwxrwx 1 root root       4 Mar 29  2009 sh -> dash

You may need to change this to point to dash as follows:

$ cd /bin
$ sudo rm sh
$ sudo ln -s bash sh

While we’re handling Ubuntu oddities building against NCurses, the terminal output library, can also be problematical. A little while ago NCurses was split in to two libraries, libncurses.so and libtinfo.so. Some badly written software will try and link explicitly with libtinfo.so directly rather than trying libncurses.so first. Ubuntu does not split these two libraries but provides just the one libncurses.so library so if you have an issue with a missing libtinfo.so you will need to add symlinks in to your library directory as follows:

$ cd /usr/lib
$ ln -s libncurses.so.5 libtinfo.so.5
$ ln -s libtinfo.so.5 libtinfo.so