set

You can save the results and put them in a file, and then modify the file so that those values are set manually when you execute this file. A great way to understand your environment values are is to study the file. Save this program, because you can execute it whenever you need to reset your environment. Just use the "." dot command to execute the file.

Solution:

Solution:

First you need to login as root. You can get the results you want by entering the set command and saving the results into a file

set > root.out

You should just get the command line prompt back.

Your answer depends on the version of UNIX you are using, but if you look at the file created in Solaris x86 you will see something similar to the following:

HOME=/
HZ=100
IFS=

LOGNAME=root
MAILCHECK=600
OPTIND=1
PATH=/usr/sbin:/usr/bin:/etc:/usr/local/bin
PS1=#
PS2=>
SHELL=/sbin/sh
TERM=vt100
TZ=US/Central

You should note that if you login as root from the console in Solaris x86, while you are running Sun's Open Windows, you will get many more lines of output then the above. The above lines are samples and your will need to examine your own output. You will need to edit the resulting file because some of the lines will not be relevant in the shell and are only temporary values created by the execution of your last command. You should remove the following lines from the above sample file

HZ=100
IFS=

OPTIND=1

The file that you would use to set your environment would then be the following:

HOME=/
LOGNAME=root
MAILCHECK=600
PATH=/usr/sbin:/usr/bin:/etc:/usr/local/bin
PS1=#
PS2=>
SHELL=/sbin/sh
TERM=vt100
TZ=US/Central

diff

Analyze this program to understand the differences in the environment between logging in as a regular user and logging in as root.

Solution:

The program to compare the two would contain the following:

diff my.out root.out > out.diff

The resulting file will look something like the following:

1,9c1,2
< HOME=/export/home/myid
< LC_COLLATE=en_US
< LC_CTYPE=en_US
< LC_MESSAGES=C
< LC_MONETARY=en_US
< LC_NUMERIC=en_US
< LC_TIME=en_US
< LOGNAME=myid
< MAIL=/var/mail/myid
---
> HOME=/
> LOGNAME=root
11,12c4,5
< PATH=/usr/bin:/usr/ucb:/usr/local/bin:.
< PS1=$
---
> PATH=/usr/sbin:/usr/bin:/etc:/usr/local/bin
> PS1=#
14,16c7,8
< PWD=/export/home/myid/web/chap2
< SHELL=/bin/sh
< TERM=ansi
---
> SHELL=/sbin/sh
ÿ TERM=vt100

The Results can be summarized n a table format as follows as follows:

You can reduce the differences by looking at the following table. Those values that are not necessary for the discussion are eliminated. This will summarize the differences between running as a regular user and running as root.

Solution:

You can do this by running the following program:

#!/bin/sh
# My test program
if test $LOGNAME = root
then
			echo "I am logged in as root"
else
			echo "I am not logged in as root"
fi

Solution:

You should note that the origin of some variables may not be clear. Generally those values that you cannot attribute to a file being executed are being set as default values by the shell. The purpose of this exercise is to help you determine, as much as possible, the origin of your environment settings.

1. /etc/profile
   

   PATH=/usr/bin:/usr/ucb:/usr/local/bin:.
   TERM=ansi

2. .profile
   

   Nothing in this particular example is attributable to the .profile file. You should examine your .profile file to see if any parameters there are set in the environment

3. Bourne Shell
   

   The following settings are assumed to be from the Bourne shell since they cannot be found to be set in any of the standard environment files we have discussed.

   IFS=
   
   LOGNAME=myid
   MAIL=/var/mail/myid
   MAILCHECK=600
   PS1=$
   PS2=>
   SHELL=/bin/sh
   HOME=/export/home/myid
   HZ=100

4. Other sources
   

   The file /etc/TIMEZONE gives the following values

   LC_COLLATE=en_US
   LC_CTYPE=en_US
   LC_MESSAGES=C
   LC_MONETARY=en_US
   LC_NUMERIC=en_US
   LC_TIME=en_US
   TZ=US/Central

   The following are produced by other sources and are generally changed from one execution of a program to another.

   OPTIND=1
   PWD=/export/home/myid/web/chap2
   _=/usr/bin/sh

Solution:

1. /etc/profile
   

   PATH=/usr/sbin:/usr/bin:/etc:/usr/local/bin
   TERM=vt100

2. .profile

   Nothing in this particular example is attributable to the .profile file. You should examine your .profile file to see if any parameters there are set in the environment

3. Bourne Shell

   The following settings are assumed to be from the Bourne shell since they cannot be found to be set in any of the standard environment files we have discussed.
   

   HOME=/
   LOGNAME=root 
   MAILCHECK=600 
   SHELL=/sbin/sh 
   IFS=
   PS1=#
   PS2=>

4. Other sources

   The file /etc/TIMEZONE gives the following values
   

   TZ=US/Central

   7)Go through the exercises in this chapter and redo them in the Bourne Shell, except this time, leave out the export command. You used this in places such as:

   Solution:

   1. export PATH
      

   2. export PS1
      

   3. Other exported variables
      

      Then you should:
      

   4. Determine which commands depend on those variables being set.
      

   5. Execute them without the variables being set.
      

   6. Export the values.
      

   7. Determine what the differences are. Be aware that some variables do not need to be exported, whereas others do.
      

   8)You have learned about some of the options to sh in this chapter. Some of those include -x and -n. Look up the following options for the Bourne Shell. Explain what effects they have on executing a shell program. Consider the option as it is used in the following:
   

   sh -option myprogram

   
   The options to be considered are as follows:
   

   1. -e
      

      Solution:

      The command will fail as soon as it hits an error in the shell program

   2. -i
      

      Solution:

      It sets an interactive mode

   3. -v
      

      Solution:

      It prints out the lines of the program as they are read from the program.

   4. Look at other options that might be useful

      Solution:

      sh -x is a very handy command because the program will print out the commands with their arguments as they are executed. It allows you to examine variable values to make sure they are properly set. It is very useful for debugging your shell commands.

   
   

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