UNIX COMMANDS
Shells
• What is a shell?
• Bourne shell
– Developed by Steve Bourne at AT&T
• Korn shell
– Developed by David Korn at AT&T
• C-shell
– Developed by Bill Joy for Berkeley Unix
How the shell works
• Shell displays a prompt.
• You type in a command.
• You press the return key.
• The shell interprets the commands you typed
and tries to find the correct programs to run.
• The kernel runs the requested programs and
returns the results to the shell.
• The shell displays the command prompt again.
Redirection <, >, >>
• <
– Redirects the standard input.
• [command] < [file name]
– The command will open the file and use its
content as its source of input.
Redirection <, >, >>
• >
– Redirects the standard output.
• [command] > [file name]
– The results of the command will be sent to the
specified file.
– Will create or overwrite the destination file.
• cat june july aug > summer2000