Re: Determing if pipe exists

[Brendan Strejcek]

Brian Seppanen wrote:

> So what I need to do is configure cfengine to detect if this file
> exists as a pipe or as a regular file. If it exists as a regular file
> delete the file and create a pipe, and make sure the ownership and
> permissions are correct.

...

> I think I've seen an ifFileExists ( ), but I'm not sure that would
> work.

You might be interested in:

http://www.cfengine.org/docs/cfengine-Reference.html#Evaluated-classes-and-special-functions

There is no test for pipeness, but IsPlain() might be useful to detect
non-pipes, depending on the logic you prefer.

This is what I would do:

    classes:
        is_pipe = (
            ReturnsZero(/bin/sh -c '
                /bin/ls -l /path/to/pipe | /bin/grep ^p >/dev/null 2>&1
            ')
        )
    
    shellcommands:
        !is_pipe::
            "/bin/rm -f /path/to/pipe"
    
            "/usr/bin/mkfifo /path/to/pipe"
    
            "/bin/chown ${pipe_ownership} /path/to/pipe"

            "/bin/chmod ${pipe_mode} /path/to/pipe"

You could also add a files: section so the permissions get verified on
every run, even when is_pipe evaluates to true.

Best,
Brendan