The following shell script myUniq is used to create a frequency list of every word in a file. When running the shell script, the first argument should be the pathname of the file to be checked. Assume we have a file as below: This is a test Test test test There are multiple tests After running the shell script, a two-column list is displayed on the screen. The first column shows what words appear, the second column shows how often they appear, for example: $./myUniq.sh test

test@3

tests@1

multiple@1

is@1

are@1

a@1

This@1

There@1

Test@1

The lines are sorted by the frequency. cat $1 | tr ' ' ' ' > temp # put all words to a new line

echo -n > file2.txt # clear file2.txt for line in _______A._______ # trace each line from temp file do

# check if the current line is visited grep -q _______B._______ file2.txt if [_______C._______] then count=`_______D.___________`

#count the number of words echo $line"@"$count >> file2.txt

# add word and frequency to file fi done sort _______E._______ file2.txt # sort the lines according to thefrequency

The following Bourne shell script and C program can accomplish the same task: read an IP address from user's input and check if the input IP address is valid or not. Shell script #!/bin/bash echo -n "Please enter the ip:" _______A._______ echo $ip|grep _______B.______________ if [_______C._______] then echo "Please enter IP address following the IP address pattern" exit fi

C programm #include int main(){ int ip1=0,ip2=0,ip3=0,ip4=0; int n=0; n=scanf("_______A2._________", _______B2.__________); if (n!=4) { printf("Please enter IP address following the IP address pattern");