I use Linux 18.04.4 LTS, and my kerner version is 4.15.0-162-generic.

My Linux server was infected by malware last night, so I run the vaccine program Clamscan and rebooted my server. After rebooting, I can not use 'sudo' operation.

obiwan@my-server:$ sudo
-bash: /tmp/9CIBU: No such file or directory
obiwan@my-server:$ sudo ls
-bash: /tmp/9CIBU: No such file or directory

But I can run bash without 'sudo' well.

obiwan@my-server:~$ cd /tmp
obiwan@my-server:/tmp$ ls
pymp-sl3fdegr                                                            systemd-private-f5c049d24eb946789a05ab83dd7f7cbb-ntp.service-IGqIwU               v3init2.log  vtmpsmkDEpZ
systemd-private-f5c049d24eb946789a05ab83dd7f7cbb-apache2.service-svZsaz  systemd-private-f5c049d24eb946789a05ab83dd7f7cbb-systemd-resolved.service-KiPmpQ  vtmpsEsWit4
obiwan@my-server:/tmp$ cat /etc/issue
Ubuntu 18.04.4 LTS \n \l

I tried hard to find any similar cases, but I couldn't find them.

There are many cases where the bash is wrong or the password file of sudo is wrong, but the case where the bash error appears in the sudo command was not found.

I really have no idea why bash needs the /tmp/9CIBU file.

If there is a way to fix it, please let me know.

Thank you a lot.