Accidentally moved `/tmp` - replacements won't persist

I did sudo mv /tmp /var/lib/apt/lists not realizing that it would move the whole folder and not just the contents.

I since do (as suggested in Accidentally deleted tmp folder)

sudo mkdir -m 1777 /tmp

on startup, but after a while it disappears again. What can I do? how can I debug this?

It seems that /tmp is renamed to /snapshot.0 (or with a higher index if other snapshots already exist).

Restart does not solve it. But shutting down without a /tmp isn't a problem either, on startup a new /tmp is there. However within 4 minutes it is renamed to another snapshot.

What happens without /tmp:

• no tab completion in bash (sometimes)
• programs such as chromium-browser and system monitor don't start
• apt-get seems to rely on /tmp as well

I currently execute sudo mv /snapshot.0 /tmp whenever /tmp disappears.

Experiments:

I start the computer(as we will see /tmp is still there apparently it survived restart) and open a terminal where I execute:

$ while true; do 
   t=$(date +%H:%M:%S);      #timestamp as hour minute seconds
   date;ls -lt / | head -3;  print out date and most recent folders in /
   ls -l /tmp        > ~/Desktop/ls.tmp.log.${t}; 
   ls -l /snapshot.0 > ~/Desktop/ls.snap.log.${t}; 
   sleep 60; 
done;

I do nothing else! log in terminal:

Di 23. Jun 19:44:12 CEST 2020
total 2097264
drwxrwxrwt  18 root root       4096 Jun 23 19:44 tmp
drwxr-xr-x  34 root root       1000 Jun 23 19:42 run
ls: cannot access '/snapshot.0': No such file or directory
Di 23. Jun 19:45:12 CEST 2020
total 2097264
drwxrwxrwt  18 root root       4096 Jun 23 19:44 tmp
dr-xr-xr-x  13 root root          0 Jun 23 19:44 sys
ls: cannot access '/snapshot.0': No such file or directory
Di 23. Jun 19:46:12 CEST 2020
total 2097264
drwxrwxrwt  18 root root       4096 Jun 23 19:44 tmp
dr-xr-xr-x  13 root root          0 Jun 23 19:44 sys
ls: cannot access '/snapshot.0': No such file or directory
Di 23. Jun 19:47:12 CEST 2020
total 2097264
drwxrwxrwt  18 root root       4096 Jun 23 19:44 tmp
dr-xr-xr-x  13 root root          0 Jun 23 19:44 sys
ls: cannot access '/snapshot.0': No such file or directory
Di 23. Jun 19:48:12 CEST 2020
total 2097264
drwxrwxrwt  18 root root       4096 Jun 23 19:44 tmp
dr-xr-xr-x  13 root root          0 Jun 23 19:44 sys
ls: cannot access '/snapshot.0': No such file or directory
Di 23. Jun 19:49:13 CEST 2020
total 2097264
drwxrwxrwt  18 root root       4096 Jun 23 19:48 snapshot.0
dr-xr-xr-x  13 root root          0 Jun 23 19:44 sys
ls: cannot access '/tmp': No such file or directory

So within 5 minutes /tmp has been renamed to /snapshot.0.

there is no difference between ls.tmp.log.19:4[4-8]:12 There is also no difference between ls.tmp.log.19:48:12 and ls.snap.log.19:49:13 so it can't be the content of /tmp.

Progress:

While I was hoping for a solution that makes things as they were before(without reinstalling the system) Giorgos Saridakis' suggestion of symlinks does work helps a lot. However I still can't start system monitor:

$ gnome-system-monitor 
cannot create temporary directory for the root file system: Permission denied

despite having all permissions set:

$ ls -lt /
total 2097264
drwxrwxrwt   8 root root       4096 Jun 27 15:21 snapshot.0
-rw-r--r--   1 root root          0 Jun 27 15:10 lifesign
...
lrwxrwxrwx   1 root root         11 Jun 23 22:12 tmp -> /snapshot.0

I guess I'll have to write a demon after all...

I wrote a script:

#!/bin/bash
while true;
do
    if [ ! -d "/tmp" ];
    then mv /snapshot.0  /tmp 2>> /home/t/tmp.rename.bg.err;
     date >> /home/t/tmp.rename.bg.log;
    fi;
    sleep 10;
done

that is executed with

sudo bash tmp.rename.sh &

after login. It's not ideal but I don't have to get into writing daemons just yet.