IT 244: Introduction to Linux/Unix
Class 15 Exercise, April 1st/6th

Log in to pe15

• Run the ssh client
  

  Use the values in the table below to connect to pe15.

  ssh configuration parameter	value
  protocol	ssh
  ssh version	2
  ssh port	22
  host	pe15.cs.umb.edu
  user name	your Unix username
  Authentication method	password

  
  
• Enter your password

  A dialog box will appear on the screen into which you must type the password for your Unix account.

Directory for this Exercise

(When you are ready for me to check this exercise, please scroll back up to where you entered these commands!)

• Go to your ex directory

      cd  ~/it244/ex

• Create an ex15 directory
  

      mkdir  ex15

• Go to your ex15 directory
  

      cd  ex15

Start Up a script Session

Execute the script command, using the --flush option

    script --flush

Running a Command in the Background

• Copy bother.sh to your ex15 directory
  

      cp  ~ckelly/course_files/it244_files/bother.sh  .

• Run bother.sh and watch it work
  

      ./bother.sh

• Stop this program
  

      Control  C

• Run this program again, but this time in the background
  

      ./bother.sh  &

  The number in brackets is the job number. The second number is the process number of the first process in the job.
  
  
• Run jobs (You'll need to type this quickly during the 5-second pause between lines being printed!)
  

      jobs

  jobs shows you the job number of all running jobs, their status, and the command line that created the job.
  
  
• Run ps (You'll need to type this quickly during the 5-second pause between lines being printed!)
  

      ps

  bother.sh is a simple script containing a loop that never ends. Inside the loop, it sleeps for 5 seconds and then prints something. When bother.sh calls sleep, it initiates a subprocess, which you see beneath bother.sh in the listing.
  
  

Bringing a Background Job to the Foreground

• Bring bother.sh to the foreground (You'll need to type this quickly during the 5-second pause between lines being printed!)
  

      fg

  You don't have to supply a job number because there is only background job.
  
  
• Suspend this job
  

      Control  Z

• Run jobs
  

      jobs

  The job still exists, but it is suspended.
  
  
• Run ps
  

      ps

  Both bother.sh and it's sleep subprocess are still there.
  
  
• Send the job to the background
  

      bg

  Again, since there is no other job, you do not have to supply a job number as an argument.
  
  
• Run jobs again (Quickly!)
  

      jobs

  The job is now in the background and has resumed running.

Killing a Background Job

• Run jobs to see the job number (Quickly!)
  

      jobs

• Use the job number to kill the job (Quickly!)
  

      kill  %JOB_NUMBER

• Run jobs to see what happened
  

      jobs

  The job has been terminated.
  
  
• Run bother.sh in the background one more time
  

      ./bother.sh  &

• Run ps to get the process number for bother.sh
  

      ps

• Use this process number to kill the job
  

      kill  PROCESS_NUMBER

• Run jobs to see what happened
  

      jobs

  The job has been terminated.
  
  
• Run ps to see your running processes
  

      ps

  bother.sh and its subprocess are gone.
  
  

The  ?  Metacharacter

• Create foo files 1 through 5
  

      touch  foo1.txt  foo2.txt  foo3.txt  foo4.txt  foo5.txt

• Create foo files 6 through 10
  

      touch  foo6.txt  foo7.txt  foo8.txt  foo9.txt  foo10.txt

• Create one last file, this one simply named foo.txt
  

      touch  foo.txt

• Obtain a long listing of the contents of your ex15 directory
  

      ls  -l

• Run a long listing using the  ?  metacharacter
  

      ls  -l  foo?.txt

  Notice that foo.txt and foo10.txt do not appear in the listing.
  
  Notice also that the foo files are in alphabetical order.

The  *  Metacharacter

• Run a long listing using the  *  metacharacter
  

      ls  -l  foo*.txt

  Notice that all the foo files appear, even foo.txt.
  
   *  means any additional characters, however many, even none.
  
  
• Run a long listing on using a single character and  * 
  

      ls  -l  f*

  You only have to enter as many characters as are needed to distinguish the files you want from the files you don't want.
  
  
• Run a long listing using more than one  * 
  

      ls  -l  f*o*

  You can use multiple instances of metacharacters

The  [  and  ]  Metacharacters

• Use the bracket metacharacters to select foo files 1 through 3
  

      ls  -l  foo[123].txt

• Use a range to list foo files 1 through 5
  

      ls  -l  foo[1-5].txt

• List all numbered foo files except 5 and 10
  

      ls  -l  foo[1-46-9].txt

• List the same files as above using a shorter search string
  

      ls  -l  foo[!5].txt

Exit Your script Session

Use the exit command

    exit

You should see a confirmation message confirming that the script is finished, resulting in a file called typescript

Bash Script for this Exercise

• Make sure you are in your ex15 directory
  

      cd ~/it244/ex/ex15

• Create the script ex15.sh
  

      nano  ex15.sh

• Write into this file the commands you used above starting with the  ?  meta-charaacter
  
  DO NOT RUN bother.sh IN THIS SCRIPT
  
  
• Save this file
  
  Save and quit.
  
  
• Make this file executable
  

      chmod 755 ex15.sh

• Test the script
  

      ./ex15.sh

  Fix any errors you find.
  
  If you have trouble, see me.