Managing Unix

1
Managing Unix

• Shell Script
• The Process
• The Jobs Control
• -Foreground and Background
• -Listing the jobs
• -Recalling the jobs
• -Killing the Jobs
• -Suspending the jobs

2
Shell Script

• A shell Script
• A file that contains commands to be executed
• To create a shell script
• 1. Create a file with vi
• 2. Put commands in it
• 3. Make the file executable

3
Our First Shell Script

• Vi inform
• The commands inside the file
• date
• pwd
• echo You have the following files
• ls
• echo Users currently logged in
• who
• echo Your login name is
• who grep USER
• echo Good Bye
• Chmod ux inform Or chmod 700 inform
• Call the file name
• inform Or ./inform

4
The Process

• A process in UNIX simply represents the running
  of a command
• The process structure in UNIX is similar to the
  hierarchical structure of directories
• The beginning process is root
• Parent processes can create child processes
• Processes can fork other processes
• When a child process is finished, execution
  returns to its parent process

5
The Processes

• To list the processes currently running
• ps
• PID TTY TIME CMD
• 15322 pts/35 000 sleep 200
• 37320 pts/35 000 -ksh
• 46212 pts/35 001 -ksh
• 61324 pts/35 000 sleep 2000
• 73748 pts/35 000 ps
• 139494 pts/35 000 -ksh

6
Listing the Processes

• To view a detailed listing of process ID numbers
  (relating child (PID) parent processes(PPID))
  enter
• ps l
• To view listing of processes for the entire
  system, enter
• ps -ef

7
Creating Filenames using

• The shell can store the PID number as a read-only
  shell variable
• echo displays the PID number that is currently
  executing
• echo ! displays the PID of the last process that
  was run in the background

8
Referring to My Phobos files

• Inform
• InformB (uses sleep to display the results of
  command better)
• InformC (the sleep time increases representing a
  bigger job being processed)
• InformD (Job results redirected to a file to be
  viewed later, but the shell is still occupied.)
• The notion of Foreground vc Background

9
The Job

• To list the jobs
• jobs
• 2 Running ../Testing/sleepygu
  y
• 1 - Running informD

10
Foreground VS. Background

• To run the job in the background
• informD
• Afterwards,The following message appears
• 1 11508
• 1 ? job number
• The second no. ? PID number
• PID (Process identification number)

11
Recalling the job

• Moving the most recent job to foreground
• fg
• or fg
• Recalling the second recent job
• fg -
• Recalling a particular job
• fg Job-number
• fg 1 fg 4

12
Killing Jobs

• Killing the most recent job
• kill
• Killing the second most recent job
• kill -
• Killing a particular job
• kill job-number
• eg kill 1 kill 4
• Killing all the processes
• kill 0
• Killing the selected process
• kill PID no.

13
Suspending a job

• Suspending a job, eg, youre writing a mail
• ltCtrlgt Z
• to go back to mail fg
• to display what you wrote so far p
• Moving a Suspended job into background
• bg
• To put a job into background, first suspend the
  job
• For a particular job
• bg job-number

14
Task1

• What command would you use to start up a ps in
  the background?
• For the next questions,refer to the following
  listing
• 2 Stopped sort /etc/passwd
• 3 - Stopped vi .cshrc
• 4 Stopped more .login
• 2.What command would you use to bring the vi
  editor into foreground?
• 3. What is the command to kill the more?
• 4. What is the command to get this listing?