Unit 1: OS installation, Linux commands and shell scripting

• Windows installation: boot from media, select edition, accept licence, custom install, partition, set user, updates and drivers.
• Dual boot: install Windows first, then Linux; GRUB boot loader offers a choice at start-up.

• Virtualisation: running multiple operating systems on one physical machine through a hypervisor — Type 1 (bare metal: VMware ESXi, Hyper-V) and Type 2 (hosted: VirtualBox, VMware Workstation).

• Benefits: safe experimentation, snapshots, running multiple OSes, testing.

bashpwd                  # print working directory
ls -l                # long listing; ls -a shows hidden files
cd /home/student     # change directory; cd .. goes up
mkdir lab4           # make directory
rmdir lab4           # remove empty directory
cp a.txt b.txt       # copy; cp -r dir1 dir2 copies folders
mv b.txt notes.txt   # move or rename
rm notes.txt         # remove file; rm -r dir removes folder
cat a.txt            # display; cat > new.txt creates (Ctrl+D to end)
chmod 755 run.sh     # change permissions

bashdf -h          # free and used space on file systems
du -sh lab4    # space used by a directory
free -h        # memory usage
lsblk          # block devices and partitions

bashps -ef               # list all processes
top                  # live view of processes
sleep 100 &          # run in background (&)
jobs                 # list background jobs; fg %1 brings to foreground
nice -n 10 ./job.sh  # start with lower priority
renice 5 -p 1234     # change priority of a running process
kill 1234            # terminate process 1234; kill -9 forces
ls -l | wc -l        # pipe: count lines of output

bashgrep "error" app.log          # lines containing error
grep -i -n "linux" notes.txt  # ignore case, show line numbers
find /home -name "*.c"        # find C files
find . -size +1M              # files larger than 1 MB
sort marks.txt                # sort lines; sort -n numeric; sort -r reverse
sort -t, -k2 -n data.csv      # sort CSV by 2nd field

bash#!/bin/bash
# Variables, parameters and conditions
name=$1                        # first command-line parameter
echo "Hello $name, you passed $# arguments"
if [ $2 -gt 50 ]; then
  echo "Pass"
else
  echo "Fail"
fi

# Loops
for i in 1 2 3 4 5; do echo "Square of $i is $((i * i))"; done
n=1
while [ $n -le 3 ]; do echo "Count $n"; n=$((n + 1)); done

# Case statement
read -p "Enter choice (1-3): " ch
case $ch in
  1) date ;;
  2) df -h ;;
  3) who ;;
  *) echo "Invalid" ;;
esac

• Run with: chmod +x script.sh then ./script.sh Riya 72.

bash#!/bin/bash
# Daily system report
report=report_$(date +%F).txt
{
  echo "System report for $(hostname) on $(date)"
  echo "--- Disk usage ---"; df -h
  echo "--- Memory ---"; free -h
  echo "--- Logged-in users ---"; who
  echo "--- Top 5 processes by memory ---"; ps aux --sort=-%mem | head -6
} > "$report"
echo "Report saved to $report"

• Scheduling with cron: crontab -e and add a line such as 0 9 * * * /home/student/report.sh to run at 9 a.m. daily.