Question

You will create a shell script that prints out the following information about the system it is run on:

• The system’s name and IP address

• How much memory the system is currently using, and how much total memory it has

• The number of CPUs of the machine

• The number of unique users on the system at that moment

When your script is run, each of these values should be clearly labeled in the output, such as Number of active users: 10 Exactly how you choose to format the information you print is up to you, so long as it is easy to interpret and the labels for each value are clear. (Adding any additional visual touches, such as a title or horizontal dividers, is permitted.) Your script should not create any intermediate files when run, and should not add anything to or remove anything from the filesystem. You may wish to query 1 the information above using commands and then store the results in variables before printing them. Much of the information above can be found and formatted using commands already introduced in this course, especially related to handling rows and columns of information. You can use the help commands discussed in class, such as man -k or apropos to help you search for useful commands if you are not sure where to begin. Once you are satisfied your script is working, you submit the script, as well as a log of you running it on at least two different lab machines, whether physical lab machines or on tuxworld. Note that you can connect to different tuxworld machines from a lab environment or from a shell in tuxworld by running the command ssh tuxn where ”n” is a single integer, such as 6 or 8. If you have developed the script on your own machine, you can transfer it to tuxworld using the scp command for testing.

1.3 Files needed for this question •

q1_sysinfo.sh: the shell script you created which prints out system information.

Answer 1

# to print hostname and IP address

HOSTNAME=$(hostname)

IP_ADDRESS=$(hostname -I)

echo -e "system's name is: $HOSTNAME"

echo -e "IP address is: $IP_ADDRESS"

# this is one way to find out memory is use and total memory

# TOTAL_MEM = free -mht | awk '{print $1"\t"$2}' | grep 'Total:'

# MEM_IN_USE = free -mht | awk '{print $1"\t"$3}' | grep 'Total:'

# another approach to find out the memory in use and total memory is

# free command gives the memory details column-wise.

#-b gives memory in bytes, -t gives a row called Total at the end

# we select the 2nd and 3rd columns to get our required information

TOTAL_MEM=$(free -bt | awk '{print $2}' | tail -n1)

MEM_IN_USE=$(free -bt | awk '{print $3}' | tail -n1)

echo -e "Total memory is: $TOTAL_MEM Bytes"

echo -e "Currently in use is: $MEM_IN_USE Bytes"

# to get the number of CPUs the computer has

NO_OF_CPUS=$(grep -c ^processor /proc/cpuinfo)

# cpuinfo contains information about every CPU or core starting from 0,1,2,3,...

# so we have to count the number of lines starting with the word "processor" using ^processor

echo -e "Number of CPUs are: $NO_OF_CPUS"

# to get the number of users currently logged in

NO_OF_USERS=$(who | grep -c .)

# who returns a list of users grep -c counts the number of lines in output

# to avoid blanks we used . (dot)

echo -e "Number of users currently logged in: $NO_OF_USERS"