4.3.6 Command search path

When you type a command into the shell, the shell searches the command in the list of directories contained in the PATH environment variable. The value of the PATH environment variable is also called the shell's search path.

In the default Debian installation, the PATH environment variable of user accounts may not include /sbin/. So if you want to run any commands such as ifconfig from /sbin/, you must change the PATH environment variable to include it. The PATH environment variable is usually set by the initialization file ~/.bash_profile, see Bash configuration, Section 3.2.