Bourne shell built-in commands
Special commands are built into the Bourne shell and run in the shell process.
Unless otherwise indicated, output is written to file descriptor 1 (standard output) and the exit status is 0 (zero) if the command does not contain any syntax errors. Input and output redirection is permitted.
The following special commands are treated somewhat differently from other special built-in commands:
: (colon) exec shift . (dot) exit times break export trap continue readonly wait eval return
The Bourne shell processes these commands as follows:
- Keyword parameter assignment lists preceding the command remain in effect when the command completes.
- I/O redirections are processed after parameter assignments.
- Errors in a shell script cause the script to stop processing.