7CCSMNSE Network Security

Lab 1

MSc Computing and Security

1

a.

date

b.

man head
man tail
man touch

c.

  • head: outputs the start of a file. -n is the number of lines to output.
  • tail: outputs the end of a file. -n is the number of lines to output.
  • touch: creates a blank new file.
  • more: a filter for paging through text one screenfull at a time.
  • less: similar to more but allows for backwards paging as well as additional enhancements.
  • man: provides paging through program manuals.

d.

head -n3 /etc/passwd
tail -n5 /etc/passwd

e.

cd ~
ls
touch file.txt
ls

Yes

2

a. We do not see our own KCL usernames in the list because we are not local-users.

b.

cut -d: -f7 /etc/passwd

c.

cut -d: -f7 /etc/passwd | uniq

d.

cut -d: -f7 /etc/passwd | sort | uniq

ef.

ls /etc/password 1>~/logfile
  • ~/logfile is empty.
ls /etc/passwd 1>~/logfile
  • ~/logfile contains
/etc/passwd

g1.

ls /etc/password 2>/dev/null || echo "Sorry, could not find file"

g2.

ls /etc/passwd && cut -d: -f7 /etc/passwd | sort | uniq

g3.

#!/bin/bash

if [ -a $1 ]; then
  cat $1
else
  echo "sorry, cant find file"
fi