Chapter 7 Study Guide - Revision history

JBackley: /* Shell Scripts */

2012-02-29T21:51:23Z

Shell Scripts

← Older revision		Revision as of 21:51, 29 February 2012
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	All work and no play makes Jack a dull boy		All work and no play makes Jack a dull boy

			[http://www.youtube.com/watch?v=t30ifxc5rtg&feature=related Example Video!]

JBackley at 21:48, 29 February 2012

2012-02-29T21:48:06Z

← Older revision		Revision as of 21:48, 29 February 2012
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	[http://www.java-samples.com/showtutorial.php?tutorialid=1345 Source]		[http://www.java-samples.com/showtutorial.php?tutorialid=1345 Source]

	==~~Escape Sequences==~~		'''Case Constructs''
			You can use the case command for multiple outcomes of a variables Start statement with “Case” End a case statement with “Esac” case backwards

			Example:

			echo –e “What is the Capital of France?
			Milan (a)
			Frankfurt (b)
			Paris (c)”
			read ANSWER
			case $ANSWER in
			a \| A ) echo –e “Incorrect”
			,,
			b \| B) echo –e “Incorrect”
			,,
			c \| C) echo –e “Correct”
			,,
			esac

			Will ask the question "What is the capital of France?" and list 3 choices. The user then types in their response (a \| A means it will accept capitalized response or not). If "a", "A", "b", or "B" are typed it will say "Incorrect". If "c" or "C" are typed it will say "Correct".

			'''&& and \|\|'''
			&& and \|\| are tests for if a command ran successfully or not

			Format: command1 (&& or \|\|) command2

			&& means if command 1 ran then run command2

			\|\| means if command1 did not then run command 2

			'''Loops'''
			Sometimes you need to run something multiple times. This is what a loop is for. A loop will keep running a set of commands until it is told to stop.

			For Loops will run the set commands for each string listed after the variable.

			for NAME in bob sue mary jane frank lisa
			do
			mail –s “here is your schedule” <newschedule $NAME
			echo “$NAME was emailed successfully”

			This script will email bob, sue, mary, jane, frank, and lisa. It will also print when they are emailed successfully.

			While Loops will run while something is true and stop once they become false.

			counter=0
			while [ $COUNTER –lt 7 ]
			do
			echo “All work and no play makes Jack a dull boy” >> /tmp/redrum COUNTER=‘expr $COUNTER + 1’
			done

			This script sets a counter to 0 and then adds 1 to the counter each time the commands are run. It will continue running until the counter is equal to 7. So the output would look like:

			All work and no play makes Jack a dull boy

			All work and no play makes Jack a dull boy

			All work and no play makes Jack a dull boy

			All work and no play makes Jack a dull boy

			All work and no play makes Jack a dull boy

			All work and no play makes Jack a dull boy

			All work and no play makes Jack a dull boy

JBackley: /* Shell Scripts */

2012-02-29T21:38:39Z

Shell Scripts

← Older revision		Revision as of 21:38, 29 February 2012
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	If the variable NAME is "Jason" it will say Hello, Jason. If it is anything else it will echo "Go Away"		If the variable NAME is "Jason" it will say Hello, Jason. If it is anything else it will echo "Go Away"

	Test Functions		Test Functions:

	-eq is equal to 5 == 6 if test 5 -eq 6 if [ 5 -eq 6 ]		-eq is equal to 5 == 6 if test 5 -eq 6 if [ 5 -eq 6 ]

JBackley: /* Shell Scripts */

2012-02-29T21:38:15Z

Shell Scripts

← Older revision		Revision as of 21:38, 29 February 2012
Line 133:		Line 133:
	Test Functions		Test Functions
	-eq is equal to 5 == 6 if test 5 -eq 6 if [ 5 -eq 6 ]		-eq is equal to 5 == 6 if test 5 -eq 6 if [ 5 -eq 6 ]

	-ne is not equal to 5 != 6 if test 5 -ne 6 if [ 5 -ne 6 ]		-ne is not equal to 5 != 6 if test 5 -ne 6 if [ 5 -ne 6 ]

	-lt is less than 5 < 6 if test 5 -lt 6 if [ 5 -lt 6 ]		-lt is less than 5 < 6 if test 5 -lt 6 if [ 5 -lt 6 ]

	-le is less than or equal to 5 <= 6 if test 5 -le 6 if [ 5 -le 6 ]		-le is less than or equal to 5 <= 6 if test 5 -le 6 if [ 5 -le 6 ]

	-gt is greater than 5 > 6 if test 5 -gt 6 if [ 5 -gt 6 ]		-gt is greater than 5 > 6 if test 5 -gt 6 if [ 5 -gt 6 ]
	-ge is greater than or equal to 5 >= 6 if test 5 -ge 6 if [ 5 -ge 6 ]
			-ge is greater than or equal to 5 >= 6 if test 5 -ge 6 if [ 5 -ge 6
			]
	string1 = string2 string1 is equal to string2		string1 = string2 string1 is equal to string2

	string1 != string2 string1 is NOT equal to string2		string1 != string2 string1 is NOT equal to string2

	string1 string1 is NOT NULL or not defined		string1 string1 is NOT NULL or not defined

	-n string1 string1 is NOT NULL and does exist		-n string1 string1 is NOT NULL and does exist

	-z string1 string1 is NULL and does exist-s file Non empty file		-z string1 string1 is NULL and does exist-s file Non empty file

	-f file Is File exist or normal file and not a directory		-f file Is File exist or normal file and not a directory

	-d dir Is Directory exist and not a file		-d dir Is Directory exist and not a file

	-w file Is writeable file		-w file Is writeable file

	-r file Is read-only file		-r file Is read-only file

	-x file Is file is executable		-x file Is file is executable

	[http://www.java-samples.com/showtutorial.php?tutorialid=1345 Source]		[http://www.java-samples.com/showtutorial.php?tutorialid=1345 Source]

	==Escape Sequences==		==Escape Sequences==

JBackley: /* Shell Scripts */

2012-02-29T21:37:34Z

Shell Scripts

← Older revision		Revision as of 21:37, 29 February 2012
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	==Shell Scripts==		==Shell Scripts==
			A set of commands saved in a text file used to automate common tasks. Any command you can use in the command line can be used in a script. hashpling (#! /bin/bash) specifies the pathname to the shell that interprets the script. “#” by itself is a comment in the script.

			Sample Script:
			#!/bin/bash
			#this is a comment
			echo “The date is:”
			date
			echo “ “
			echo “People logged in:”
			who

			'''Escape Sequences''
			Used to change output of text in the terminal.

			Common ones:
			\??? -A 3 digit ASCII character (in octal)
			\\ -Backslash
			\a –ASCII beep
			\b –Backspace
			\c –prevents a new line between commands
			\n –New Line
			\t –Horizontal Tab
			\v –Vertical Tab

			'''Read Command'''
			Saves user’s input and places it in a variable used by a script. In the example the script asks for a name, when you type it in it is saved to the NAME variable.

			Echo –e “Who are you? \c”
			Read NAME
			Echo “Hello $NAME”

			Who are you? '''Jason''' <--User's typed response
			Hello Jason

			'''Decision Constructs'''
			Not all scripts will run straight through, sometimes you need to see if something installed or the user typed something. Decision constructs allow a script to do different things in different scenarios.

			Format of an If construct:
			If “something is true”
			Then
			Do these commands
			Else
			Do these commands

			Example:

			if [ $NAME = “Jason”]
			then
			echo –e “Hello, Jason”
			else
			echo –e “Go Away”

			If the variable NAME is "Jason" it will say Hello, Jason. If it is anything else it will echo "Go Away"

			Test Functions
			-eq is equal to 5 == 6 if test 5 -eq 6 if [ 5 -eq 6 ]
			-ne is not equal to 5 != 6 if test 5 -ne 6 if [ 5 -ne 6 ]
			-lt is less than 5 < 6 if test 5 -lt 6 if [ 5 -lt 6 ]
			-le is less than or equal to 5 <= 6 if test 5 -le 6 if [ 5 -le 6 ]
			-gt is greater than 5 > 6 if test 5 -gt 6 if [ 5 -gt 6 ]
			-ge is greater than or equal to 5 >= 6 if test 5 -ge 6 if [ 5 -ge 6 ]
			string1 = string2 string1 is equal to string2
			string1 != string2 string1 is NOT equal to string2
			string1 string1 is NOT NULL or not defined
			-n string1 string1 is NOT NULL and does exist
			-z string1 string1 is NULL and does exist-s file Non empty file
			-f file Is File exist or normal file and not a directory
			-d dir Is Directory exist and not a file
			-w file Is writeable file
			-r file Is read-only file
			-x file Is file is executable
			[http://www.java-samples.com/showtutorial.php?tutorialid=1345 Source]

	==Escape Sequences==		==Escape Sequences==

JBackley: /* Shell variables */

2012-02-29T21:26:34Z

Shell variables

@@ Line 61: / Line 61: @@
 To create a variable, specify the name of the variable followed by = and the new contents. Variable identifies can contain alphanumeric characters, the "–" character, or the "_" character. They must not start with a number. They are typically capitalized to follow convention (HOME, PATH, etc.). To create a variable called MYVAR with the contents “This is a sample variable” you would use these command:
   MYVAR="This is a sample variable"
 ==Shell Scripts==
 ==Escape Sequences==

JBackley: /* Shell variables */

2012-02-29T21:24:44Z

Shell variables

@@ Line 33: / Line 33: @@
 ==Shell variables==
 ==Shell Scripts==
 ==Escape Sequences==

JBackley: /* Command input and output */

2012-02-29T21:19:06Z

Command input and output

← Older revision		Revision as of 21:19, 29 February 2012
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	cat </etc/issue		cat </etc/issue

			Redirection only occurs between a command and a file. However you can send stdout of 1 command to another command as stdin. You can do this by using the pipe shell metacharacter "\|" This symbol can be created by pressing the shift key along with the \ key. Common use for piping is to reduce the amount of information displayed.

	==Shell variables==		==Shell variables==
	==Shell Scripts==		==Shell Scripts==
	==Escape Sequences==		==Escape Sequences==

JBackley: /* Command input and output */

2012-02-29T21:17:29Z

Command input and output

@@ Line 1: / Line 1: @@
 ==Command input and output==
 ==Shell variables==
 ==Shell Scripts==
 ==Escape Sequences==

JBackley: Created page with "==Command input and output== ==Shell variables== ==Shell Scripts== ==Escape Sequences=="

2012-02-29T21:12:36Z

Created page with "==Command input and output== ==Shell variables== ==Shell Scripts== ==Escape Sequences=="

New page

==Command input and output==
==Shell variables==
==Shell Scripts==
==Escape Sequences==