Difference between "./ "and "sh" and the default SHELL | Extra shell features | Ubuntu Dash

During the last days I wrote some shell scripts to keep my development environments in sync. When it came to arrays I experienced some weird problems.

fl0@fl0-m0thership:~/AutoPkgUpdater$ sh MakePlist.sh f00
MakePlist.sh: 25: Syntax error: "(" unexpected

Guess what's at line 25? Right, an array declaration...The weird thing: I was able to directly declare an array in the shell like the following:

fl0@fl0-m0thership:~/AutoPkgUpdater$ a=( one two three)

fl0@fl0-m0thership:~/AutoPkgUpdater$ echo ${a[1]}
two

To make things even more complex, running the script like "./MakePlist.sh" worked, NO Syntax error. Ok - here's the trick:

"...Running it as ./script.sh will make the kernel read the first line (the shebang), and then invoke bash to interpret the script. Running it as sh script.sh uses whatever shell your system defaults sh to (on Ubuntu this is Dash, which is sh-compatible, but doesn't support some of the extra features of Bash)..." [StackOverflow]

So you may change your "/bin/sh" to bash?

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

To make dash code "/bin/bash" compatible you may read the following:

https://wiki.ubuntu.com/DashAsBinSh