chain Fish commands via `&&` or `||`

Question

In Bash/ZSH and other shells, I am used to using && and ||.

Is there any equivalent in Fish?

Solution 1

The logical operators you're used to, are supported since fish 3.0.0, released on 2018-12-28.

From the v3 release notes:

• fish now supports && (like and), || (like or), and ! (like not), for better migration from POSIX-compliant shells (#4620).

Solution 2

Fish doesn't have a special syntax for a logical AND (&&) or a logical OR (||).

Instead, you can use the commands and and or, which verify the previous command's exit status and act accordingly:

command1
and command2

command1
or command2

Furthermore – just like in bash – you can use a semicolon ; to execute two commands one after the other:

command1 ; command2

This allows using a more familiar syntax:

command1 ;and command2
command1 ;or command2

See http://fishshell.com/docs/current/tutorial.html#tut_combiners

Comments

[Elliott Beach]

This syntax now supported on the master branch and will be released in Fish 3.0 (github.com/fish-shell/fish-shell/commit/…)

[aboy021]

There's an open github issue to add support for this syntax: && doesn't work · Issue #150 · fish-shell/fish-shell

[Petr Peller]

This allows using a more familiar syntax: is very subjective

[Elliott Beach]

;and is less readable than && as the semicolon suggests a logically disjoint operation. It's visually jarring.

[Dennis]

@Elliott I agree, but Fish doesn't give you a choice.

[balupton]

do note though that in fish and bourne shells, AND and OR operators have the same order, unlike C based languages: unix.stackexchange.com/a/88851/50703

[math2001]

@dennis which is a good thing: there's only one option, and you don't have to choose, it's already chosen for you. Plus I think that using a "native" solution instead of implementing a new syntax if far better, even though it might now look as good (and, as petr said, it's very subjective).

[Admin]

You can't do command1 and command2 though, command 2 will never be run because "and" will be considered as argument 1 for command1, and command2 will be considered as argument 2 for command1. For example if true and true; echo yes; end won't work because fish will think you're passing the arguments "and true" to the command true. if true; and true; echo yes; end is the correct way.