UNIX for Dummies Questions & Answers

# I take in the user prefix (lets say its q123 because eveyone who works in dept Q 
# starts with a Q123 as their id. Joe may be Q123rt, Sally Q123ff etc.
usrr="$1"

 
# Now I look to see all people logged on with the prefix entered on command line
loggedOn=$(who | cut -d' ' -f1 | grep $usrr)
 
# Here I check to see if employees exist
employee=$(cat /etc/passwd | grep "$usrr")

 
# Here I am taking that prefix and pulling the names of all logged in users then 
# reversing them to a first name, last name format
output=$(cat /etc/passwd | grep "$loggedOn" | cut -d: -f5 | tr -s ',' ' ' | sed 's/\(.*\) \(.*\)/\2 \1/')

# Now, my script I have thus far
if [ -z "$employee" ]
then
echo "Invalid prefix"
exit 2
fi
if [ -z "$loggedOn" ]
then
echo "No such user is on right now"
exit 1
else
echo $(who | awk '{print "Hello " $output}')
fi

#! perl
die "Input a pattern as argument!" if (not $ARGV[0]);
@loggedOn = `who | cut -f1 -d " " | grep "^$ARGV[0]" | sort | uniq `;
die "Pattern doesn't match into any of the logged on users" if (not scalar @loggedOn);
foreach $i (@loggedOn) {
chomp $i;
$fullname = `grep "$i:" /etc/passwd | cut -d: -f5 | tr -s ',' ' ' | sed 's/\(.*\) \(.*\)/\2 \1/'`;
chomp $fullname;
print "WARNING: $i is not in passwd file\n" if (not $fullname);
next if not $fullname;
print "Hello ***$fullname\n";
}

#! perl
$passwdfile = "passwd";
die "Input a pattern as argument!" if (not $ARGV[0]);
@loggedOn = `who`;
foreach $name (@loggedOn) { $n = (split(/\s+/,$name))[0]; next if $n !~ /^$ARGV[0]/i; $users{$n} = 1; }
   die "Pattern doesn't match into any of the logged on users" if (not scalar keys %users);
  open (file, $passwdfile) || die "couldn't open $passwdfile: $?";
  foreach $line (<file>) {
          ($username,$fullname) = (split(/:/,$line))[0,4];
  $fullname =~ s/,/ /g;
  $full{$username} = $fullname;
}
foreach $i (sort keys %users) {
  if (not exists $full{$i}) {print "WARNING: $i is not in passwd file\n"; next;}
    print "Hello ***$full{$i}\n";
}