Unix Jeopardy 4, 3/31/2016. CSC 352, UNIX Dr. D. Parson, Session 4 of Unix Jeopardy, Shell Programming

Transcription

1 Unix Jeopardy 4, 3/31/2016 CSC 352, UNIX Dr. D. Parson, Session 4 of Unix Jeopardy, Shell Programming

2 IniEal setup Use write parson TTY and paste your one-line answer when you are ready. When you need to write a mule-line if, while, or for control construct, test it first, then use up-arrow to pull a one-liner from the bash history. Make your terminal window full screen before doing that, so the command characters don t get garbled. Hit control-d to exit before the next queseon. Have at least 1 and probably 2 other terminal windows logged into acad for trying stuff.

3 QuesEon 1 What is the full ps command for showing the users and associated program names for running processes? Use the a and correct o opeons of ps. My ps output looks like this at the moment: RUSER COMMAND frye sendnulls skuns844 emacs (etc.)

4 ps -ao "%u %c" Answer 1

5 QuesEon 2 Show the ps command or command pipeline modificaeon to the previous answer that removes the RUSER heading line, and sorts the printed results according to user name. Previous ps command answer 1: ps -ao "%u %c

6 Answer 2 ps -ao "%u %c" grep v RUSER sort OR ps -ao "%u %c" --sort user grep v RUSER

7 QuesEon 3 Show the ps command or command pipeline modificaeon to the previous answer that removes the "RUSER COMMAND heading line, and sorts the printed results according to command name. Previous answer: ps -ao "%u %c" grep v RUSER sort ps -ao "%u %c" --sort user grep v RUSER

8 Answer 3 ps -ao "%u %c" --sort cmd grep v RUSER

9 QuesEon 4 Show the ps command or command pipeline modificaeon to the previous answer that removes the "RUSER COMMAND heading line, and sorts the printed results according to user as the primary sort key, command name as the secondary sort key. Previous answer: ps -ao "%u %c" --sort cmd grep v RUSER

10 Answer 4 ps -ao "%u %c" --sort user,cmd grep v RUSER

11 QuesEon 5 Write a shell funceon called myps() that runs the previous command pipeline, so you do not have to keep typing it in the upcoming answers. Previous command pipeline: ps -ao "%u %c" --sort user,cmd grep v RUSER

12 Answer 5 funceon myps() { ps -ao "%u %c" --sort user,cmd grep v RUSER; }

13 QuesEon 6 Loop through the result lines of the myps command using a for or a while loop, and print an integer index in front of each line: 1 carelli vim 2 cpero025 emacs etc.

14 Answer 6 set -- `myps` ; i=1 ; while [ $# -gt 0 ]; do echo $i $1 $2; shiq; shiq; i=`expr $i + 1`; done OR i=1 ; odd=1 ; for str in `myps`; do if [ $odd -eq 1 ]; then u=$str; else echo $i $u $str; i=`expr $i + 1`; fi; odd=`expr 1 - $odd`; done

15 QuesEon 7 (conenued on next page) Write another shell funceon myps2() that takes 1 or more command line arguments represeneng users, and prints the same results as myps(), but for only for those users. Hint: ls -d * egrep 'mybin myscript play in ~parson displays only those listed files. funceon myps() { ps -ao "%u %c" --sort user,cmd grep v RUSER; }

16 QuesEon 7 Hint: ls -d * egrep 'mybin myscript play in ~parson displays only those listed files. funceon myps() { ps -ao "%u %c" --sort user,cmd grep v RUSER; } $ myps2 parson frye # EXAMPLE RUN frye sendnulls frye sleep parson bash parson egrep parson grep parson ps

17 Answer 7 funceon myps2() { pauern=$1; shiq; while [ $# -gt 0 ]; do pauern="$pauern $1"; shiq; done; myps egrep $pauern; }

18 QuesEon 8 Write another shell funceon myps3() that checks to see whether it has at least one command line argument. If it does NOT have an argument, it must write an error message to STANDARD ERROR. Do not exit, since we are running from the terminal. If it does have at least one argument, it must call myps2 with all of its arguments.

19 Answer 8 funceon myps3() { if [ $# -lt 1 ]; then echo "Missing command line arguments" >&2; else myps2 $*; fi; }