Week 8

Shell Scripting Basics

	Command files
	shell scripts
	test command [ for bash, sh and ksh ]
	if statement
	Loops

Grep/egrep review 

	[]
	{}
	\(\)
	^ $

Shell Scripting Topics

	Quotes ' " ` and \
        test command
                string comparison
                integer comparison
                file attribute check

        exit status

        command line arguments $1 $2 .. $9 ${10} $# $* "$@"

        Passing arguments from command line

        Shell variables user defined, positional and keyword

        if statement

        case statement

        for statement

        while statement

egrep/grep review


        egrep '.*_.*CPU.*_.*_' 

        egrep '^$'

        egrep '.'

        egrep '.*'

        ifconfig -a |grep "^[a-z0-9]*:"

        /usr/bin/egrep -v '^[       ]*(#|$)' /etc/dfs/dfstab

        /usr/bin/grep '^[   ]*share' /etc/rmmount.conf

        /usr/bin/dirname $0 | grep "/etc/rc"

        /usr/bin/grep -v \^\# /etc/defaultrouter

        /sbin/mount | /usr/bin/egrep '^/tmp(/| )'

Egrep metacharacters

.	-> any single character

[]	-> set of characters, range of characters
		[ABC]  [0-9]
	
		[^1234567890]

examples:

	[1-9]	
	[^A-Z123]	

root|bin	--> alternation 

A|B		--> match A or B

*		--> 0 or more occurrences of the prev. RE

	.*	--> 0 or more occ. of any character.
	AB*	--> A
	[a-m]*	--> 0 or more occ. of lowercase a thru m

+		--> 1 or more occ. of the prev. RE
	.+	--> 1 or more of any character
	AB+	--> AB


\{n\}		--> exactly n occ. of the prev. RE
		ABC\{3\}	--> ABCCC

		(ABC)\{3\}	--> ABCABCABC