If else statement if file exists

[Eugene Sapozhnikov]

I am trying to figure out a way to use a if statement to run multiple sets of commands depending if one file exists, but I am unable to find any good documented ways of doing this.

Basic rough layout of what i would like to achieve is this:

Any help on getting the correct syntax for the if statement would be appreciated 

if file /volumes/vol1 exists { exec { generate_loopback_tor: command => "/sbin/losetup /dev/loop6 /volumes/tor", unless => "/sbin/losetup -a| /bin/grep \"/volumes/tor\"", } 

exec { generate_encrypt_tor:

    command => " /sbin/cryptsetup create tor ",

    unless => "/usr/bin/test -e /dev/mapper/tor",

 }

exec { generate_mount_tor: command => "/bin/mount /dev/mapper/tor /usr/local/tor", unless => "/bin/mount | /bin/grep \"/usr/local/tor\"", }

} else { exec { generate_empty_file_tor: command => "/bin/dd of=/volumes/tor bs=256M count=0 seek=1", unless => "/usr/bin/test -e /volumes/tor", } exec { generate_loopback_tor: command => "/sbin/losetup /dev/loop6 /volumes/tor", unless => "/sbin/losetup -a| /bin/grep \"/volumes/tor\"", } exec { generate_encrypt_tor: command => "/bin/echo \XXXXXXXXXX\" | /sbin/cryptsetup create tor /dev/loop6 -", unless => "/usr/bin/test -e /dev/mapper/tor", } exec { generate_zero_tor: command => "/bin/dd if=/dev/zero of=/dev/mapper/tor count=512 bs=1024", unless => "/sbin/fdisk -lu | /bin/grep \"/dev/mapper/tor\"", } exec { generate_mkfs_tor: command => "/sbin/mke2fs -j -O dir_index /dev/mapper/tor ", onlyif => "/sbin/parted -l | /bin/grep \"Error: /dev/mapper/tor: unrecognised disk label\"", } exec { generate_mount_tor: command => "/bin/mount /dev/mapper/tor /usr/local/tor", unless => "/bin/mount | /bin/grep \"/usr/local/tor\"", }

 

}

[Ellison Marks]

There are some parameters to the exec type that you could use, such as creates, onlyif and unless. However, the pseudocode you have above has the execs in your initial if block being run every time puppet runs, it seems. Is that really what you want?

[Eugene Sapozhnikov]

I do want the first part of If to run every time if the file exists, as the unless and onlyif that are part of the exec commands are safety checks to make sure to not overwrite the volume.

I wanted to use the if else condition to determine between creating a new volume vs unecrypting an existing one and mounting it

[Eugene Sapozhnikov]

Basicly I am looking for the syntax to use as a conditional in the if statement for a file exists check.

On Monday, August 18, 2014 2:45:23 PM UTC-7, Eugene Sapozhnikov wrote:

[Yanis Guenane]

If your file `/volumes/vol1` could be managed by Puppet somehow, you
could use if defined(File['/volumes/vol1']) as a condition.

Not sure if it is possible in your case,

--
Yanis Guenane

On 08/19/2014 12:04 PM, Eugene Sapozhnikov wrote:
> Basicly I am looking for the syntax to use as a conditional in the
> if statement for a file exists check.
>
> On Monday, August 18, 2014 2:45:23 PM UTC-7, Eugene Sapozhnikov
> wrote:
>>
>>
>>
>> I am trying to figure out a way to use a if statement to run
>> multiple sets of commands depending if one file exists, but I am
>> unable to find any good documented ways of doing this.
>>
>> Basic rough layout of what i would like to achieve is this:
>>
>> Any help on getting the correct syntax for the if statement would
>> be appreciated
>>
>>
>>

>> if file /volumes/vol1 exists { *exec { generate_loopback_tor:

>> command => "/sbin/losetup /dev/loop6 /volumes/tor", unless =>

>> "/sbin/losetup -a| /bin/grep \"/volumes/tor\"", } *
>>
>> *exec { generate_encrypt_tor: command => " /sbin/cryptsetup

>> create tor ", unless => "/usr/bin/test -e /dev/mapper/tor",
>> }exec { generate_mount_tor: command => "/bin/mount
>> /dev/mapper/tor /usr/local/tor", unless => "/bin/mount |

>> /bin/grep \"/usr/local/tor\"", } }* else { exec {

[Eugene Sapozhnikov]

Yeah sadly in this case the vol1 gets created as one part of the else statement, so my goal is on the second run to determine if it exists to just encrypt it and mount it instead of going through the whole build procedure.

[jcbollinger]

On Tuesday, August 19, 2014 11:10:26 AM UTC-5, Yanis Guenane wrote:

If your file `/volumes/vol1` could be managed by Puppet somehow, you
could use if defined(File['/volumes/vol1']) as a condition.

Not sure if it is possible in your case,

Whether it's possible is irrelevant, because that's not correct in any case.  That use of the defined() function tests whether File['/volumes/vol1'] is in the catalog -- and even then it tests only at a particular instant during catalog compilation, ignoring any later addition of such a resource to the catalog.  AND it will return true if File['/volumes/vol1'] has ensure => absent.  None of that has anything to do with whether said file/directory is actually present on the target system at the start of the run, or at any random point in the middle of a run.

Do not use defined().  Ever.

John

[jcbollinger]

On Monday, August 18, 2014 4:45:23 PM UTC-5, Eugene Sapozhnikov wrote:

I am trying to figure out a way to use a if statement to run multiple sets of commands depending if one file exists, but I am unable to find any good documented ways of doing this.

Your main alternatives are:
1) Add a file existence/nonexistence test to each Exec resource, in either its 'onlyif' or its 'unless' command.  Of course, this is repetitive and it doesn't work for resources of other types than Exec.

1a) You could address at least the repetitiveness by wrapping up your separate commands into one (or more) scripts, and exec'ing that instead of execing each command individually.

2) You could create a custom fact that tests the file's existence (just before the beginning of each run).  Then you could use that fact's value in your conditional logic.


John

[Eugene Sapozhnikov]

Thanks for clearing it up.

I ended up just using onlyif and unless in each exec statement. this allowed me to rcycle the same commands between the scenario of creating the volume and mounting and encrypting the volume and mounting it. 

Thanks 

[Yanis Guenane]

Mea culpa for a misleading information.

Thanks John for the explanation, I didn't know about the 'particular
instant during the catalog compilation'. And for the ensure => absent,
I haven't thought about that one.

--
Yanis Guenane

On 08/20/2014 09:11 AM, jcbollinger wrote:
>
>
> On Tuesday, August 19, 2014 11:10:26 AM UTC-5, Yanis Guenane
> wrote:
>>
>> If your file `/volumes/vol1` could be managed by Puppet somehow,
>> you could use if defined(File['/volumes/vol1']) as a condition.
>>
>> Not sure if it is possible in your case,
>>
>
>

> Whether it's possible is irrelevant, because that's not *correct*