Linux Shells by Example

1.5. The Environment and Inheritance

When you log on, the shell starts up and inherits a number of variables, I/O streams, and process characteristics from the /bin/login program that started it. In turn, if another shell is spawned (forked) from the login or parent shell, that child shell (subshell) will inherit certain characteristics from its parent. A subshell may be started for a number of reasons: for handling background processing; for handling groups of commands; or for executing scripts. The child shell inherits an environment from its parent. The environment consists of process permissions (who owns the process), the working directory, the file creation mask, special variables, open files, and signals.

1.5.1. Ownership

When you log ...