Shell Modes and Initialization
In this section, we will first discuss the startup procedure for the various Bourne-type shells, and then we will examine the different modes of execution for a shell.
After you log in, a shell is executed on your behalf. When this shell starts executing, it is uninitialized. In this state, several parameters required for its proper operation are not defined. The shell undergoes a process called initialization that defines these parameters. The steps and files involved in initialization are different in each shell, so we will examine the process used by each of the Bourne-type shells individually. In general each of the shells uses default or system-wide configuration files located in the ...