Are you receiving syntax errors when running a shell script on Ubuntu 6.10 (Edgy Eft)? If so, you might want to check what shell you are using. While testing scripts for the LCA A/V Team a few months ago, I discovered that the Ubuntu developers decided to symlink /bin/sh to dash, for faster and less memory-intensive script execution. For POSIX-compliant scripts, this isn’t a problem at all. However, there are many third-party scripts which call /bin/sh but use shell-specific (typically bash) syntax. They can be fixed by altering their first line to call the most appropriate shell, for example:

#!/usr/bin/env bash

env makes it possible to call bash, wherever it may lie. While my Ubuntu and Gentoo systems have a /bin/bash, there are other distributions which have /usr/bin/bash or /usr/local/bin.bash.

While you can and should fix your own scripts to operate in this way, constantly mending others’ mistakes can become tiresome. You can return your /bin/sh to point to bash with the following command:

$ sudo dpkg-reconfigure dash

When asked if you wish to install dash as /bin/sh, tell it to go to hell

Note that bash does use more memory, but on a modern desktop machine the difference is negligible. This change will not affect the default login shell, since that is already bash.

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