Question

Write shell script code that displays the process tree on a Linux machine. The process tree should show the process identifier of each process. Those processes that have the same ancestor should be sorted by process identifier instead of by name. The process tree should show the full names of all threads, if any and available. Whenever the user identifier associated with a process differs from the user identifier associated with the parent of that process, the process tree should show the transition.

#!/bin/bash

while [[ $REPLY != x ]]; do
clear

echo -e "Launch utilities:\n 1. Process Tree\n 2. Process States\n 3. Threads\n"

read -p "Enter selection [1-3], or type x to exit: " REPLY

if [ $REPLY == 1 ]; then
   echo -e "\n"

   #identify a command that displays the tree of processes in Linux
#identify the options of the command you have found that meet the requirements described in section "Process Tree" of the description of Homework 03
#put the command here, followed by the options. For example, if the command is called displayprocesstree, and the options are -a, -b, and -c, the command would appear as follows:
# displayprocesstree -abc

read void
   clear
fi

if [ $REPLY == 2 ]; then
#identify the command that displays a list of processes on the system. identify the options of that command that can include the state of each process in the output

   read void
   clear
fi

if [ $REPLY == 3 ]; then
#display a string that asks the user to enter the pid of one of the processes
#read a pid from the user onto a variable
# display the threads created by that process

read void
clear
fi

done

Answer 1

#!/bin/bash

while [[ $REPLY != x ]]; do
clear

echo -e "Launch utilities:\n 1. Process Tree\n 2. Process States\n 3. Threads\n"

read -p "Enter selection [1-3], or type x to exit: " REPLY

if [ $REPLY == 1 ]; then
echo -e "\n"
pstree -psa $$
ps -aef --forest
read void
clear
fi

if [ $REPLY == 2 ]; then
ps u
read void
clear
fi

if [ $REPLY == 3 ]; then
read -p "Enter PID: " p_id
ps -T -p $p_id
read void
clear
fi

done

Code	Meaning
D	Uninterruptible sleep (usually IO)
R	Running or runnable (on run queue)
S	Interruptible sleep (waiting for an event to complete)
T	Stopped, either by a job control signal or because it is being traced.
W	paging (not valid since the 2.6.xx kernel)
X	dead (should never be seen)
Z	Defunct (“zombie”) process, terminated but not reaped by its parent.

Code	Meaning
<	high-priority (not nice to other users)
N	low-priority (nice to other users)
L	has pages locked into memory (for real-time and custom IO)
s	is a session leader
l	is multi-threaded (using CLONE_THREAD, like NPTL pthreads do)
+	is in the foreground process group

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