[Short Tip] Add a path entry to Nushell

Adding a path in nushell is pretty straight forward: the configuration is done in ~/config/nu/config.toml in the [path] section.

If you don’t have it, make sure that the default entries are listed there as well when you start bringing in your own directories. The fastest way to populate your configuration with the default entries is to ask nushell to do it: config set path $nu.path

Next, add the directories you need:

path = ["/usr/local/bin", "/usr/local/sbin", "/usr/bin", "/usr/sbin","/home/rwolters/go/bin"]

In the above example I added the default go binary directory to the list.

[Short Tip] Define an alias in Nushell

A few days ago I decided to switch my main shell to nushell. It offers next generation capabilities similar to other modern shells like Powershell:

Rather than thinking of files and services as raw streams of text, Nu looks at each input as something with structure. For example, when you list the contents of a directory, what you get back is a table of rows, where each row represents an item in that directory.

Nushell Philosophy

This switch feels like the biggest shell related change for me since I switched from Windows Command Prompt to Bash. Even the switch from Bash to ZSH was small in comparison.

As part of this I have to relearn how to do a lot of things. For example, defining an alias is totally different.

The nushell configuration takes place in ~.config/nu/config.toml. To add an alias there, add the section startup if it is not there already, and add a list item there:

startup = [
    "alias evince = flatpak run org.gnome.Evince",
    "alias ll = ls -la",
    ]

In the above example two aliases are given, one to call ls, and one for launching evince via flatpaks.

Image by julia roman from Pixabay

[Short Tip] Quickly copy files to Samsung Galaxy S20+ on Fedora 32

Transferring files from a Fedora 32 machine to an Android phone is usually not a problem: plugin in it (via USB), unlock screen, make sure that USB connection is set to file transfer, and open the phone in Nautilus.

However, I recently had to get a new phone, decided to opt for the Samsung Galaxy S20+ – and there I was not able to write files to the device:

rsync: open "/run/user/1000/gvfs/mtp:host=SAMSUNG_SAMSUNG_Android_R58N23ZDCVN/Phone/appdata/2020-04-12_23-38 - foldersync.db" failed: Operation not supported (95)

Note that other phones made no problems so far. And things got even more weird when I realized that I was able to create folders – but not files?!

After the usual tricks (enabling USB debugging, switching cables, etc.) I realized that this might be a special problem with the implementation of mtp by this phone. So instead of using libmtp, wich is used by default by for example gvfs, I tested other mtp implementations – and found simple-mtpfs, which worked like a charm:

$ sudo simple-mtpfs -l
1: SamsungGalaxy models (MTP)
$ sudo simple-mtpfs --device 1 /mnt
# you have to acknowledge access to the phone on the phone screen
# then you have to mount it again
$ sudo simple-mtpfs --device 1 /mnt
$ sudo rsync --verbose --progress --size-only --omit-dir-times --no-perms --recursive --inplace /home/liquidat/backup/ /mnt/Phone/

The performance is good – way better than trying to copy files via gphoto2, btw 😉

Image by Martin Pyško from Pixabay

[Short Tip] Flatten nested dict/list structures in Ansible with json_query

A few days ago I was asked how to best deal with structures in Ansible which are mixing dictionaries and lists. Basically, the following example was provided and the questioned remained how to deal with this – for example how to flatten it:

    myhash:
      cloud1:
        region1:
          - name: "city1"
          - size: "large"
          - param: "alpha"
        region2:
          - name: "city2"
          - size: "small"
          - param: "beta"
      cloud2:
        region1:
          - name: "city1"
          - size: "large"
          - param: "gamma"

I was wondering a lot how to deal with this – after all dict2items only deals with dicts and fails when it reaches the lists in there. I also fooled around with the map filter, but most of my results also required some previous knowledge about the data structure, were only acting by providing “cloud1.region1” or similar.

The solution was the json_query filter: it is based on jmespath and can deal with the above mentioned structure by list and object projections:

  tasks:
  - name: Projections using json_query
    debug:
      msg: "Item value is: {{ item }}"
    loop: "{{ myhash|json_query(projection_query)|list }}"
    vars:
      projection_query: "*.*[]"

And indeed, the loop does create a simplified output of all the elements in this nested structure:

TASK [Projections using json_query] **********************************************************
ok: [localhost] => (item=[{'name': 'city1'}, {'size': 'large'}, {'param': 'alpha'}]) => {
    "msg": "Item value is: [{'name': 'city1'}, {'size': 'large'}, {'param': 'alpha'}]"
}
ok: [localhost] => (item=[{'name': 'city2'}, {'size': 'small'}, {'param': 'beta'}]) => {
    "msg": "Item value is: [{'name': 'city2'}, {'size': 'small'}, {'param': 'beta'}]"
}
ok: [localhost] => (item=[{'name': 'city1'}, {'size': 'large'}, {'param': 'gamma'}]) => {
    "msg": "Item value is: [{'name': 'city1'}, {'size': 'large'}, {'param': 'gamma'}]"
}

Of course, some knowledge is still needed to make this work: you need to know if you are projecting on a list or on a dictionary. So if your data structure changes on that level between executions, you might need something else.

Image by Andrew Martin from Pixabay

[Short Tip] Accessing Nautilus mounted locations via shell/terminal

When using Gnome, it is quite convenient to mount remote locations directly in Nautilus. As an example, I often mount my Google Drive work folder, also my personal NextCloud instance.

While this makes it easy to work with remote accessible files from within Gnome tools, it is less obvious how to access for example files from within a shell like gnome-terminal.

Nautilus uses FUSE to mount remote locations. You can find more in the Gnome documentation GVfs.

With this knowledge, the solution is this directory:

$XDG_RUNTIME_DIR/gvfs

In that directory you will find the actual fuse mounts of the remote locations linked from within Nautilus:

$ ls -1 $XDG_RUNTIME_DIR/gvfs
'dav:host=nc.bayz.de,ssl=true,prefix=%2Fremote.php%2Fwebdav'
'google-drive:host=redhat.com,user=ABCDEF'

Those are directories, so you can just work with them as with usual directories and change into them, edit files, etc. Of course, depending on the internet connection and the endpoint and the protocol the interactions will not be comparable to working on files on your local SSD. But it might be just enough for your use cases.

Thanks to strugee for this detailed comment on StackExchange.