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?

score 266 · Accepted Answer · edited Apr 16 '13 at 08:11

266

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.

edited Apr 16 '13 at 08:11

Community

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answered May 27 '11 at 13:15

ignar

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In other words it's got a short-circuit behaviour – Peter Chaula Jul 12 '18 at 08:49
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@peter Which one? The `;` one or the `&&` one? Or do you mean both? – Shayan Aug 29 '19 at 18:55
@Shayan, the `&&`. – Peter Chaula Aug 29 '19 at 19:06
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So you would prefer to run `sudo apt update && sudo apt upgrade` and not `sudo apt update; sudo apt upgrade`, right? – Vthechamp Feb 03 '21 at 16:38

score 74 · Answer 2 · edited May 30 '17 at 15:12

74

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... ;)

edited May 30 '17 at 15:12

Christian P

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answered May 27 '11 at 18:33

clt60

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To be safer, I'd use `rm -rf /tnp/test` – melvynkim Mar 08 '14 at 08:45
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To be even safer it is better to use `rm /tnp/test/ -rf` to prevent deadly enter missclick – radrow Jun 01 '18 at 12:49
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^C ^C ^\ ahaha that made me chuckle. – John Hunt Feb 09 '23 at 15:48

score 35 · Answer 3 · answered May 27 '11 at 13:12

35

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.

answered May 27 '11 at 13:12

Pascal Cuoq

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Fredrik Pihl · Answer 4 · 2011-05-27T13:28:10.907

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&& 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.

edited May 27 '11 at 13:28

answered May 27 '11 at 13:14

Fredrik Pihl

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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). – Scott H Oct 15 '21 at 19:29

score 10 · Answer 5 · answered May 27 '11 at 13:13

10

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.

answered May 27 '11 at 13:13

Dave Costa

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Here's a link to the bash manual: http://www.gnu.org/software/bash/manual/bashref.html#Lists – glenn jackman May 27 '11 at 14:05

score 6 · Answer 6 · edited May 27 '11 at 19:08

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&& allows for conditional execution while ; always has the second command being executed.

In e.g. command1 && command2, command2 will only execute when command1 has terminated with exit 0, signalling all went well, while in command1 ; command2 the second command will always be executed no matter what the result was of command1.

edited May 27 '11 at 19:08

chl

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answered May 27 '11 at 13:15

Marcel

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score 3 · Answer 7 · answered May 27 '11 at 15:48

3

&& is logical AND in bash. Bash has short-circuit evaluation of logical AND. This idiom is a simpler way of expressing the following:


cmd1;rc=$?
if [ $rc -eq 0 ]; then
   cmd2
fi

Whereas the ; version is merely:


cmd1
cmd2

answered May 27 '11 at 15:48

frankc

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Bash/sh - difference between && and ;

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