Что за команда "`"(гравис) в командной оболочке bash?
man bash
Command Substitution
Command substitution allows the output of a command to replace the com‐
mand name. There are two forms:
$(command)
or
`command`
Bash performs the expansion by executing command and replacing the com‐
mand substitution with the standard output of the command, with any
trailing newlines deleted.