Commands placed between parentheses are executed in a new child shell process rather than the shell process that received the commands as input.
This can be useful if you want a command to run in a different directory or with other alterations to its environment, without affecting the current shell process.
shell-prompt: (cd /etc; ls)
Since the commands above are executed in a new shell process, the shell process that printed "shell-prompt: " will not have its current working directory changed. This command has the same net effect as the following:
shell-prompt: pushd /etc
shell-prompt: ls
shell-prompt: popd
Make sure you are using the latest version of this document.
Carefully read one section of this document and casually read other material (such as corresponding sections in a textbook, if one exists) if needed.
Try to answer the questions from that section. If you do not remember the answer, review the section to find it.
Write the answer in your own words. Do not copy and paste. Verbalizing answers in your own words helps your memory and understanding. Copying does not, and demonstrates a lack of interest in learning.
Check the answer key to make sure your answer is correct and complete.
DO NOT LOOK AT THE ANSWER KEY BEFORE ANSWERING QUESTIONS TO THE VERY BEST OF YOUR ABILITY. In doing so, you would only cheat yourself out of an opportunity to learn and prepare for the quizzes and exams.
Important notes:
Show all your work. This will improve your understanding and ensure full credit for the homework.
The practice problems are designed to make you think about the topic, starting from basic concepts and progressing through real problem solving.
Try to verify your own results. In the working world, no one will be checking your work. It will be entirely up to you to ensure that it is done right the first time.
Start as early as possible to get your mind chewing on the questions, and do a little at a time. Using this approach, many answers will come to you seemingly without effort, while you're showering, walking the dog, etc.
Show a single Unix command that runs pwd and produces the output "/etc", without changing the CWD of the shell process.