Question

Create a new script named ifcommand.sh that accepts a username as input and checks to see if that user is logged in. If the user is logged in, print "yes", otherwise print "no"

Example;

example@general:~$ ./ifcommand.sh cjingers
yes

Answer 1

Answer) First I test whether user has enter only one username or not, then I check by the who and grep command that user has loggedin or not because who command give the details of all the users who have logged in and grep is used to search the username from the who command. I bypass the output by /dev/null

Any doubt please comment me.

vi ifcommand.sh

if test $# -gt 1
then
echo "Type only one username"
exit
fi
if (who|grep $1)>/dev/null
then
echo "yes"
else
echo "no"
fi

save the file

screenshot