Alternatives module: Add a check that the path to the executable exist

[khomutoff]

SUMMARY

By default, the alternatives tool does not verify the path to the executable that the link should point to. I've added a check that should prevent installation of requested path if the path does not exist in a system.

ISSUE TYPE

• Bugfix Pull Request

COMPONENT NAME

alternatives

ANSIBLE VERSION

ansible 2.2.0.0
  config file = /etc/ansible/ansible.cfg
  configured module search path = Default w/o overrides

[ansibot]

cc @DavidWittman @mulby
click here for bot help

[pilou-]

This update seems unnecessary: update-alternatives command already checks that requested path exists and returns an error when requested path doesn't exist.

For example:

$ cat /var/lib/dpkg/alternatives/w
auto
/usr/bin/w
w.1.gz
/usr/share/man/man1/w.1.gz

$ sudo update-alternatives --install /usr/bin/w w /tmp/notexistent 100              
update-alternatives: error: alternative path /tmp/notexistent doesn't exist

[khomutoff]

@pilou- I've tested on one of our Fedora Linux instances:

$ sudo update-alternatives --install /usr/bin/java open_jdk /tmp/notexistent 2000

$ sudo update-alternatives --display open_jdk
open_jdk - status is auto.
 link currently points to /tmp/notexistent
/tmp/notexistent - priority 2000
Current `best' version is /tmp/notexistent.

$ sudo update-alternatives --version
alternatives version 1.7

$ ls /tmp/notexistent
ls: cannot access /tmp/notexistent: No such file or directory

[pilou-]

Oops, I only checked on Debian :-/ Then this PR is useful :-) !

[calfonso]

rebuild_merge