Bash/sh - difference between && and ;

I normally use ; to combine more than one command in a line, but some people prefer &&. Is there any difference? For example, cd ~; cd - and cd ~ && cd - seems to make the same thing. What version is more portable, e.g. will be supported by a bash-subset like Android's shell or so?

If previous command failed with ; the second one will run.

But with && the second one will not run.

This is a "lazy" logical "AND" operand between operations.

I'm using && because a long time ago at the nearby computer:

root# pwd
/
root# cd /tnp/test; rm -rf *
cd: /tnp/test: No such file or directory
...
... and after a while ...
...   
^C

but not helped... ;)

cd /tnp/test && rm -rf * is safe... ;)

In cmd1 && cmd2, cmd2 is only executed if cmd1 succeeds (returns 0).

In cmd1 ; cmd2, cmd2 is executed in any case.

Both constructs are part of a POSIX-compliant shell.

&& means to execute next command if the previous exited with status 0. For the opposite, use || i.e. to be executed if previous command exits with a status not equal to 0 ; executes always.

Very useful when you need to take a particular action depending on if the previous command finished OK or not.