st Semester 2021 TRODUCTION TO UNIX (All Sections ) Depending on the following Snapshot of a bash terminal

st Semester 2021 TRODUCTION TO UNIX (All Sections ) Depending on the following Snapshot of a bash terminal, What is the output of the last co ranas-mbp:- rana$ cat|wc & (1) 1080 ranas-mbp:- ranas psf UID PID PPIDC STIMETTY TIME CMD 228 1072 1073 02:58PM Hys00:00.04 -bash 228 1079 1072 0 3:09PM Itys000 0:00.01 cat 228 1080 1072 0 3:09PM tys000 0.0001 WC ranas-mbpranas echo SS 1072 228 1073 1080 ere to search

The correct answer and explanation is:

Output of the Last Command:

The output of the last command cat | wc & would not be visible directly to the terminal because the command is run in the background due to the & symbol. However, we can analyze what happens when this command is executed:

1. cat without any arguments reads from standard input (stdin).
2. The pipe (|) redirects the output of cat to wc.
3. wc is the “word count” utility, which reads input and counts lines, words, and characters.

Since no input is provided to cat, it will wait for input indefinitely unless interrupted.

When executed in the background using &, the command does not display its output directly to the terminal but instead creates background processes for cat and wc.

Observations from the Process Table (ps):

• The ps command shows processes and their details.
• PID 1079: A background process for cat is running.
• PID 1080: A background process for wc is also running.
• Both processes are waiting for input.

Explanation:

1. Command Breakdown:
   • cat | wc &: Runs cat and wc in a pipeline but in the background.
   • Both cat and wc wait for input because the cat command is not provided with input, and wc depends on cat.
2. Process States:
   • The ps output shows that cat and wc are running on tty000 with minimal CPU time. They are idle, waiting for input.
3. Why No Visible Output:
   • Because the command is executed in the background, its output (if any) is not immediately visible in the terminal.
   • To see the output, you would need to bring the processes to the foreground or provide input explicitly (e.g., via file redirection).
4. Practical Outcome:
   • Without input, the commands will remain active until killed or input is provided.

Final Answer:

The output of the last command is not directly visible because it runs in the background, awaiting input. If terminated without input, there is no meaningful output.