Anything you design your script to solve.

It is not possible to answer this question completely without writing a book, if not several books.

This script will list the contents of the /usr/bin directory in single column format...

#!/bin/bash

ls -1 /usr/bin

and this script does exactly the same thing except it performs a stream search and replace operation substituting all lower case letters in the range from m-z with the upper case letter X using the stream editor, sed. The character between the words bin and sed is the pipe symbol (shift backslash).

#!/bin/bash

ls -1 /usr/bin|sed s/[m-z]/X/g

NOTE: It is important to issue the

$ chmod 700 script_name

command after saving your script. It is not necessary to use the name script_name, you may concoct your own name for your script. :)

A final example of a slightly more complex script which uses a subroutine and fork to generate an arbitrary number of fibonacci numbers.

#!/bin/bash

if [ -z ${1} ]; then

echo "Pass the number of fibonacci numbers you wish generated as the argument to this script."

exit

## Decided to add comma insertion every 3rd digit to make the

## output easier to read. Friday the 13th of September, 2013.

## Friday the 13th?

commify () {

typeset text=${1}

typeset bdot=${text%%.*}

typeset adot=${text#${bdot}}

typeset i commified

(( i = ${#bdot} - 1 ))

while (( i>=3 )) && [[ ${bdot:i-3:1} == [0-9] ]]; do

commified=",${bdot:i-2:3}${commified}"

(( i -= 3))

done

echo "${bdot:0:i+1}${commified}${adot}"

}

LIMIT=${1}

COUNT=0

N1=0

N2=1

FIBONACCI=0

## Might as well just print the first two as they can't possibly

## have any other value than 0 and 1.

echo "And our first ${LIMIT} FIBONACCI numbers are...:"

echo "0"

echo "1"

while [ ${COUNT} -le ${LIMIT} ]; do

# FIBONACCI=$(($N1 + $N2))

FIBONACCI=`echo "${N1} + ${N2}"|bc -l`

COMMA_FORMATTED_RESULT=`commify "${FIBONACCI}"`

echo "${COMMA_FORMATTED_RESULT}"

N1=${N2}

N2=${FIBONACCI}

(( COUNT++ ))

done

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