Ubuntu Toggle default sh for bash or dash

Tag: Run enter to toggle its dash Linu ECIF spec system

Ubuntu Toggle default sh for bash or dash1 bash and Dash

Starting with Ubuntu 6.10, the default is to use Dash (Thedebian almquist shell) instead of bash (the Gnubourne-again shell).

But the login shell is bash. The reason is that dash is faster and more efficient, and it complies with the POSIX specification. Ubuntu runs a lot of shell scripts when it starts up, and using dash can speed up startup.

1.1 What is bash?

Bash (GNU bourne-again shell) is the default shell for many Linux platforms, and in fact, there are many other shells used on Unix, like Tcsh, CSH, Ash, BSH, Ksh, and so on, shell script is roughly similar, When you learn a shell, the other shells will quickly get started, and most of the time, a shell script can often be used on many kinds of shells.

1.2 What is dash?

Dash is the standard command interpreter for the system. The current

Version of Dash is in the process of being changed to conform with the

POSIX 1003.2 and 1003.2A specifications for the shell.

2 Toggle Bash and dash2.1 view and use

Take a look at the command first ls -l /bin/sh

/bin/sh, Dash

We'll find out that Ubuntu is using Dash for default

2.2 Toggle SH to bash

If you want to modify the default sh, you can use the command

sudo dpkg-reconfigure Dash

Then select No

Execute after success

Ll/bin/sh

The result is:/bin/sh -> bash

Modified successfully!

2.3 Toggle sh for Dash

Of course we can also use

sudo dpkg-reconfigure Dash

Change the sh back.

3 links

The syntax difference between dash and bash

Ubuntu Toggle default sh for bash or dash