将多个项目附加到fish shell中的路径（相当于：+ =）

Question

For example chruby has a user define additional ruby paths via. the following:

RUBIES +=( /opt/jruby-1.7.0 "$HOME/src/rubinius" )

Is there a nice way to accomplish this in fish?

Answer 1

All fish variables are arrays. So in theory this would be as simple as

set -x RUBIES $RUBIES /opt/jruby-1.7.0 "$HOME/src/rubinius"

Unfortunately fish won't automatically convert that array to a string of colon separated values when it exports the var. At the present time fish only does that for PATH and MANPATH.

You can do it like this:

set -x RUBIES "$RUBIES:/opt/jruby-1.7.0:$HOME/src/rubinius"

But that assumes RUBIES has already been set; otherwise you get a string with a leading colon which may, or may not, have special meaning for any software using the var. Dealing with that is straightforward:

if set -q RUBIES[1]
    set -x RUBIES "$RUBIES:/opt/jruby-1.7.0:$HOME/src/rubinius"
else
    set -x RUBIES "/opt/jruby-1.7.0:$HOME/src/rubinius"
end

Too, if you're using fish 2.3 (soon to be released) or a fish built from git head you can use the new "string" builtin to split and join the string on colons:

set rubies (string split ':' $RUBIES)
set rubies $rubies /opt/jruby-1.7.0 "$HOME/src/rubinius"
set -x RUBIES (string join ':' $rubies)