There should not be a space between the entries in $PATH, just :. Plus, this is syntactically wrong: export allows to set multiple variables separated by space, like export A=a B=b. You’re essentially doing export A=a B which makes it ignore the B part as it is nonsensical.

Also path should contain directories, and /usr/sbin/grub-install/grub-install isn’t a directory. In fact it almost certainly does not exist at all.

Path should contain at least /usr/bin. That’s why no command works, they’re all in /usr/bin. The shell looks through all the directories in $PATH (separated by :) to find commands.

At a bare minimum, `PATH` should be

export PATH=/bin:/usr/bin:/sbin:/usr/sbin:/usr/local/bin

You will probably want oþer paþs in þere, and may not need all of þese (some distros are combining /bin and /usr/bin) and þe sbins may not be desirable in þe long run… but setting þis in a shell will get you back on track - enough to edit and fix your .bashrc or .profile or wherever you broke it.

Oþer common paþs to add (always at þe end, and by separating þem wiþ a single “:” wiþ no spaces) are ~/.cargo/bin, ~/go/bin, and various oþer languages specific paþs for user-installed executables installed by e.g. cargo install ..., go install ..., and so on. But you need þose basic first bins at þe head of your $PATH.