The command could not be located because '/bin' is not included in the PATH environment variable.

[Nekochef]

I haven't opened my WSL for a month, it worked properly last time, but when I opened it this time, every basic command cannot be executed:

shadowstep@Shadowstep:~$ echo $SHELL
/bin/bash
shadowstep@Shadowstep:~$ ll
Command 'ls' is available in '/bin/ls'
The command could not be located because '/bin' is not included in the PATH environment variable.
ls: command not found
shadowstep@Shadowstep:~$ bash
Command 'bash' is available in '/bin/bash'
The command could not be located because '/bin' is not included in the PATH environment variable.
bash: command not found
shadowstep@Shadowstep:~$ /bin/bash
Command 'lesspipe' is available in the following places
 * /bin/lesspipe
 * /usr/bin/lesspipe
The command could not be located because '/usr/bin:/bin' is not included in the PATH environment variable.
lesspipe: command not found
Command 'dircolors' is available in '/usr/bin/dircolors'
The command could not be located because '/usr/bin' is not included in the PATH environment variable.
dircolors: command not found
Command 'ls' is available in '/bin/ls'
The command could not be located because '/bin' is not included in the PATH environment variable.
ls: command not found
shadowstep@Shadowstep:~$ source ~/.profile
Command 'lesspipe' is available in the following places
 * /bin/lesspipe
 * /usr/bin/lesspipe
The command could not be located because '/usr/bin:/bin' is not included in the PATH environment variable.
lesspipe: command not found
Command 'dircolors' is available in '/usr/bin/dircolors'
The command could not be located because '/usr/bin' is not included in the PATH environment variable.
dircolors: command not found
Command 'ls' is available in '/bin/ls'
The command could not be located because '/bin' is not included in the PATH environment variable.
ls: command not found
shadowstep@Shadowstep:~$

if I manually enter:
export PATH=/bin:/usr/bin:/usr/local/bin:/sbin:/usr/sbin:/usr/local/sbin:
Then those commands are fixed. However my pre-defined environment variables exist in ~/.bashrc still cannot be executed.
if I execute echo $PATH at the startup, the paths are:
/home/shadowstep/bin:/home/shadowstep/.local/bin:/home/shadowstep/UNIX/Package/modeltestng,
which is equivalent to executing source ~/.profile plus the last line of ~/.bashrc, but my .bashrc file has four lines at last:

export PATH="/home/shadowstep/miniconda3/bin:$PATH"
export PATH=~/src/edirect:$PATH
export DISPLAY=:0
export PATH="/home/shadowstep/UNIX/Package/modeltestng"

WSL just loaded .profile and the last line of .bashrc

Is it a bug? How should I fix it?

[therealkenc]

but my .bashrc file has four lines at last:
[...]
export PATH="/home/shadowstep/UNIX/Package/modeltestng"

That last line just blew away the proceeding export PATH assignments. You want:

export PATH=/home/shadowstep/UNIX/Package/modeltestng:$PATH