RubyGems question: install vs. update

Ruby
1

This must be obvious, but what’s the difference between “gem install”
and “gem update”?

I would have thought that “gem update” would do a gem install plus a
gem cleanup, effectively updating your current version. But that
doesn’t seem to be the case.

Jeff

2

On Apr 29, 2009, at 14:16, Jeff wrote:

This must be obvious, but what’s the difference between “gem install”
and “gem update”?

I would have thought that “gem update” would do a gem install plus a
gem cleanup, effectively updating your current version. But that
doesn’t seem to be the case.

gem update will update a named gem if there’s a newer version, gem
install will always install.

gem update can update all gems if you don’t list any.

3

On Apr 29, 5:16 pm, Eric H. [email protected] wrote:

install will always install.
Hi Eric,

But when I try to update a named gem, I get the new version, but also
still have the old version (if I do gem list I can see both
versions). So maybe I’m missing what you mean by “update” - looks to
me like it simply installed the new one alongside the old one, no
different than if I had done “gem install” to install the latest
version.

I’m currently on RubyGems 1.3.2.

Thanks again,
Jeff

4

On Wed, Apr 29, 2009 at 9:01 PM, Jeff [email protected] wrote:

But when I try to update a named gem, I get the new version, but also
still have the old version (if I do gem list I can see both
versions). So maybe I’m missing what you mean by “update” - looks to
me like it simply installed the new one alongside the old one, no
different than if I had done “gem install” to install the latest
version.

I’m currently on RubyGems 1.3.2.

RubyGems supports having many versions of a gem installed on the same
system, which is often necessary for dealing with libraries that
depend on a particular version of a project.

The difference between gem update gemname and gem install gemname is
that gem update is essentially a no-op if you already have the latest
gem installed, where gem install will download and install the gem
even if you already have it.

-greg

5

7stud – wrote:

Gregory B. wrote:

The difference between gem update gemname and gem install gemname is
that gem update is essentially a no-op if you already have the latest
gem installed, where gem install will download and install the gem
even if you already have it.

In addition,

…oh, yeah. Sometimes updating doesn’t work! For instance, I was
unable to update rubygems itself using rubygems. I eventually had to
download the latest version of rubygems and install locally.

6

Gregory B. wrote:

The difference between gem update gemname and gem install gemname is
that gem update is essentially a no-op if you already have the latest
gem installed, where gem install will download and install the gem
even if you already have it.

In addition, if you issue the update command with no filename, for
example:

$ gem update

rubygems will search your local gem directory and update all the gems
contained therein with the latest versions.

If you don’t need the old versions, then after either updating or
installing you can use the command

$ gem cleanup

to get rid of the old versions.

7

On Thu, Apr 30, 2009 at 1:04 AM, 7stud – [email protected]
wrote:

$ gem update

rubygems will search your local gem directory and update all the gems
contained therein with the latest versions.

Read upwards. Eric already let the OP know about this.

8

On Thu, Apr 30, 2009 at 1:06 AM, 7stud – [email protected]
wrote:

…oh, yeah. Sometimes updating doesn’t work! For instance, I was
unable to update rubygems itself using rubygems. I eventually had to
download the latest version of rubygems and install locally.

(sudo) gem update --system

normally works to install the latest version of ruby gems, although it
has been known to fail for certain combinations of old installed, and
new versions.

–
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale
WWR: http://www.workingwithrails.com/person/9021-rick-denatale
LinkedIn: http://www.linkedin.com/in/rickdenatale