Hi,
I’m trying to make some space on my phone because i have this notification :
“no more space in /boot device”
So i tried that :
“sudo apt autoremove”
but after the system tell me :
“purism does not appear in the sudoers group”
So i tried
sudo usermod -aG sudo purism
and type password and have still have :
“purism does not appear in the sudoers group”
Is someone can help me ?
Thanks
Looks like you try to use sudo to change the setting that makes using sudo possible in the first place.
So if the user purism really isn’t in the group you probably have to use su to become root. Then you can add the user to the group. After that you can leave the root shell. Maybe you have to start a new shell or re-login to make the system recognize the changes.
I did not check weather the call of usermod with the given parameters is correct.
Possibly, booting Jumpdrive (on the phone, using a host computer) is the right answer here.
You can address both problems
a) check free space on the /boot partition
b) sort out sudo
I know that OP ask something specific, but my L5 also says low disc space, both on rootfs and boot.
I have a very hard time to get enough space especially on boot. Is there a go-to solution for this?
I might have experienced this in the beginning, but I cannot recall what I did to solve it.
Edit:
Well, somehow “sudo apt autoremove” just solved my issue for now so I managed to get the phone up to date. However, I’m still interested what others experience.
Hi Rhodes-x, it happened to me too today. I found this thread:
and as written there, I solved giving this command in terminal:
sudo apt autopurge
Hope it’ll work for you too! 
Please, then let me know.
Thank you
Thanks @veleno. 
I’ll try it out next time it is a issue.
Right now it seems to be as clean as it can get, i.e there is noting to be done by autopurge.
Edit: After apt autoremove and with the update succeeded I have 149mb free space in boot.
Please use sudo apt clean && sudo apt autoclean from time to time (explained within man apt-get command).