Special Built-in Utilities

• break - exit from for, while, or until loop
• colon - null utility
• continue - continue for, while or until loop
• dot - execute commands in current environment
• eval - construct command by concatenating arguments
• exec - execute commands and open, close, or copy file descriptors
• exit - cause the shell to exit
• export - set export attribute for variables
• readonly - set read-only attribute for variables
• return - return from a function
• set - set or unset options and positional parameters
• shift - shift positional parameters
• times - write process times
• trap - trap signals
• unset - unset values and attributes of variables and functions