CIS 527 - Command Line Interfaces & Simple Scripts

CIS 527

Command Line Interfaces & Simple Scripts

Linux Commands

pwd - Get current directory
cd - Change directory
ls - List files
mkdir - Make new directory
rmdir - Remove directory
rm - Remove file
cp - Copy file
mv - Move file

Linux Commands 2

grep - Search for text
wc - Get word count
cat - Print files
sort - Sort items
apropos - Find commands
whereis - Find command location
whatis - Find command descriptions
man - Find command help

Linux File Permissions

ls -al - Find file permissions
- [user][group][others]
- r = read; w = write; x = execute
- rwxr--r--
chmod - Change file permissions
chown - Change file ownership
sudo - Run as administrator
script - Record commands in text file

PowerShell Commands

Get-Location - Get current directory
Set-Location - Change directory
Get-ChildItem - List files
New-Item - Make new directory
Remove-Item - Remove directory
Remove-Item - Remove file
Copy-Item - Copy file
Move-Item - Move file

PowerShell Commands 2

Select-String - Search for text
Measure-Object - Get word count
Get-Content - Print files
Sort-Object - Sort items
Get-Command - Find commands
Where-Object - Find object location
Get-Help - Find command descriptions
Get-Help - Find command help

PowerShell Commands 3

Get-Alias - Find Aliases for commands
Select-Object - Get parts of output
Out-GridView - Output to a grid view
Out-File - Output to a file
Add-Content - Add content to files
Add-Item - Create new files/folders
'-Whatif' flag - See command steps
Start-Transcript - Record commands

File Output

> Output to a file (overwrite)
>> Output to a file (append)
| Pass output of one command to another

Special Directories

./ Current Directory
../ Parent Directory
~/ Home Directory
/ System Root
- Previous Directory (Linux)
$HOME\ Home Directory (Windows)

Building Shell Scripts

Open a new file using a text editor

$ nano script.sh

Add the following header at the top

#!/bin/bash

Building Shell Scripts

Input commands below (1 per line)

cd ~/bin
ls -al

Save the file (CTRL + X) and run

$ chmod u+x ./script.sh
$ ./script.sh

Shell Hello World

#!/bin/bash

echo "Hello World"
exit 0

Shell Hello World

echo "Hello World"

echo prints text

exit 0

exit stops the command

Simple Script

#!/bin/bash
#batman.sh

if (( $# < 1 || $# > 1 )); then
  echo "Usage: batman.sh <name>"
  exit 1
fi

if [ "$1" = "Batman" ]; then
  echo "Hello Mr. Wayne"
elif [ "$1" = "Robin" ]; then
  echo "Welcome back Mr. Grayson"
else
  echo "Intruder alert!"
fi
exit 0

Shell Script Parameters

$1 - First Parameter
$2 - Second Parameter
...
${10} - Tenth Parameter
${11} - Eleventh Parameter

$# - Number of Parameters
$* - All Parameters (as String)

Conditionals

if (( $# < 1 || $# > 1 )); then

Double parens for arithmetic evaluation

if [ "$1" = "Batman" ]; then

Square brackets for logical test
(using Linux 'test' command)

Loop Script

#!/bin/bash
#listfiles.sh

files=`ls $* 2> /dev/null`
for afile in "$files"; do
    echo "$afile"
done
exit 0

Loops

files=`ls $* 2> /dev/null`

Declares a new variable $files
Backticks (`) get output of command

for afile in "$files"; do

Perfom commands below once for each item in $files

Environment Variables

Stores information about the system that can be used in scripts

$ printenv

Prints the current environment variables

PATH Variable

Tells your system where to look for binary files and scripts

$ export PATH=$PATH:$HOME/bin

Add a folder to the path
(Add this line to ~/.bashrc to make it permanent)

Building PowerShell Scripts

Open the PowerShell ISE (search for it on the Start menu)
You can also use a text editor such as Notepad
To be able to run them, open an Administrative Powershell and enter "Set-ExecutionPolicy Unrestricted"

PowerShell Scripts

Write-Host "Hello World"
return

PowerShell Parameters

Param(
  [string]$computerName,
  [string]$userName
)

Simple Script

Param(
  [string]$user
)
if ( -not ($user)){
    Write-Host "Usage: batman.ps1 <name>"
    return
}
if ($user.CompareTo("Batman") -eq 0){
    Write-Host "Hello Mr. Wayne"
}else{
    if ($user.CompareTo("Robin") -eq 0){
        Write-Host "Welcome back Mr. Grayson"
    }else{
        Write-Host "Intruder alert!"
    }
}
return

Loop Script

param(
  [string]$path
)

$files = Get-ChildItem $path

foreach($file in $files){
    Write-Host $file.name
}

Environment Variables

Control Panel > System and Security > System > Advanced System Settings > Environment Variables

Add a new variable called PATH to the user variables and give it the value "C:\Users\cis527\bin"

Review

Printing Text
Accepting Parameters
If Statements
Looping
Environment Variables

Select Statement

#!/bin/bash
#simplemenu.sh
OPTIONS="Build Run Clean Quit"
select opt in $OPTIONS; do
  if [ "$opt" = "Build" ]; then
    echo "Building project..."
  elif [ "$opt" = "Run" ]; then
    echo "Running project..."
  elif [ "$opt" = "Clean" ]; then
    echo "Cleaning project..."
  elif [ "$opt" = "Quit" ]; then
    echo "Exiting..."
    break
  else
    echo "Invalid Input"
  fi
done
exit 0

Select Statement

User Input

#!/bin/bash
#simpleinput.sh
echo "Input your name and press [ENTER]"
read name
echo "Welcome $name!"
exit 0

User Input

Scheduling Tasks - Cron

Cron allows you to schedule tasks to run a specific times

Very useful for tasks that need done regularly

Cron HowTo

$ crontab -e

Edit the current cron schedule

$ crontab -l

View the current cron schedule

$ sudo crontab -e

Edit the root cron schedule

Crontab

Crontab Timing

m h dom mon dow
15 5 * * 0 5:15 AM every Sunday (0)
*/10 8 - 16 * * 1-5 every 10 min 8AM - 5PM weekdays
0 0 1 1 1 run at 12:00 AM every January 1 and every Monday
@reboot run once, after system starts

PowerShell Menu

$title = "Select Options"
$message = "Choose an option to perform"
$build = New-Object `
  System.Management.Automation.Host.ChoiceDescription `
  "&Build", "Build the project"
$run = New-Object `
  System.Management.Automation.Host.ChoiceDescription `
  "&Run", "Run the project"
$clean = New-Object `
  System.Management.Automation.Host.ChoiceDescription `
  "&Clean", "Clean the project"
$quit = New-Object `
  System.Management.Automation.Host.ChoiceDescription `
  "&Quit", "Quit"
$options = `
  [System.Management.Automation.Host.ChoiceDescription[]] `
  ($build, $run, $clean, $quit)
$result = $host.ui.PromptForChoice($title, $message, $options, 0)
switch ($result)
{
    0 {"You selected Build"}
    1 {"You selected Run"}
    2 {"You selected Clean"}
    3 {"You selected Quit"}
}

PowerShell Menu

PowerShell Input

$name = Read-Host `
    "Input your name and press [ENTER]"
Write-Host "Welcome $name!"

PowerShell Input

Windows Task Scheduler

Windows Create Task

Assignments

Lab 1 - Building Secure Workstations: Due Monday January 30th by 10:30 AM