Bash/sh - difference between && and ;

Question

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?

Solution 1

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.

Solution 2

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... ;)

Solution 3

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.

Solution 4

&& 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.

Solution 5

Commands separate by ; are executed sequentially regardless of their completion status.

With &&, the second command is executed only if the first completes successfully (returns exit status of 0).

This is covered in the bash manpage under Lists. I would expect any Unix-like shell to support both of these operators, but I don't know specifically about the Android shell.

View more solutions

Comments

[glenn jackman]

Here's a link to the bash manual: gnu.org/software/bash/manual/bashref.html#Lists

[melvynkim]

To be safer, I'd use rm -rf /tnp/test

[radrow]

To be even safer it is better to use rm /tnp/test/ -rf to prevent deadly enter missclick

[Peter Chaula]

In other words it's got a short-circuit behaviour

[Shayan]

@peter Which one? The ; one or the && one? Or do you mean both?

[Peter Chaula]

@Shayan, the &&.

[Vthechamp]

So you would prefer to run sudo apt update && sudo apt upgrade and not sudo apt update; sudo apt upgrade, right?

[Scott H]

Note that if you combine && and ||, then you must put the && first. Otherwise, the && executes if either the original or the || command succeeds (exits with 0 status).